Optical filter, and solid-state image pickup device and camera module using the optical filter

ABSTRACT

The problem of the present invention is to overcome drawbacks of conventional optical filters such as near-infrared cut filters and to provide an optical filter which generates little scatted light even during light absorption and has excellent transmittance property. The optical filter of the present invention is characterized by containing a squarylium-based compound and a compound which absorbs or quenches fluorescence of the squarylium-based compound. The optical filter of the present invention preferably contains a near-infrared absorbing dye containing a squarylium compound (A) and at least one compound (B) selected from the group consisting of a phthalocyanine-based compound (B-1) and a cyanine-based compound (B-2).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/351,268, which in turn is a national stage ofInternational Application No. PCT/JP2012/076388, filed Oct. 12, 2012,which claims priority to Japanese Patent Application No. 2011-227134,filed Oct. 14, 2011, and to Japanese Patent Application No. 2012-214584,filed Sep. 27, 2012. The contents of these applications are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to an optical filer and a device using anoptical filter. More particularly, the present invention relates to anoptical filter containing a specific dye compound of solvent-solubletype, and a solid-state image pickup device and a camera module each ofwhich uses the optical filter.

BACKGROUND ART

In solid-state image pickup devices, such as video cameras, digitalstill cameras and cellular phones having camera function, a CCD or CMOSimage sensor that is a solid-state image sensor of color image is used.In such a solid-state image sensor, silicon photo diode havingsensitivity to near-infrared rays that cannot be perceived by human eyeis used in its light-receiving section. For such a solid-state imagesensor, it is necessary to make correction of visibility so that anatural color might be obtained when an image is seen with human eye,and an optical filter (e.g., near-infrared cut filter) to selectivelytransmit or cut rays of specific wavelength region is frequently used.

As such near-infrared cut filters, those manufactured by various methodshave been used in the past. For example, in Japanese Patent Laid-OpenPublication No. 1994-200113 (patent literature 1), a near-infrared cutfilter in which a transparent resin is used as a base material and anear-infrared absorbing dye is incorporated into the transparent resinis described.

Optical filters, such as the near-infrared cut filter containing anear-infrared absorbing dye described in the patent literature 1, arewidely known. As a result of earnest studies, the present applicant hasfound that a squarylium-based dye among near-infrared absorbing dyes isexcellent particularly in steepness in absorption and height of visiblelight transmittance, and has proposed a near-infrared cut filtercontaining a squarylium-based dye and having a wide viewing angle inJapanese Patent Laid-Open Publication No. 2012-8532 (patent literature2).

However, since the squarylium-based dye generally has fluorescence inview of its molecular structure, it sometimes generates scattered lightduring light absorption, and the image quality of camera is sometimeslowered.

CITATION LIST Patent Literature

Patent literature 1: Japanese Patent Laid-Open Publication No.1994-200113

Patent literature 2: Japanese Patent Laid-Open Publication No. 2012-8532

SUMMARY OF INVENTION Technical Problem

The object of the present invention is to overcome drawbacks ofconventional optical filters such as near-infrared cut filters and toprovide an optical filter which generates little scatted light evenduring light absorption and has excellent transmittance property and adevice using the optical filter.

Solution to Problem

The present inventors have earnestly studied in order to attain theabove object. As a result, the present inventors have found that anoptical filter which generates little scattered light during lightabsorption and is excellent in transmittance property is obtained byusing, as near-infrared absorbing dyes, a squarylium-based compound anda specific compound that absorbs or quenches fluorescence of thesquarylium-based compound in combination, and they have accomplished thepresent invention. Embodiments of the present invention are shown below.

[1] An optical filter containing a near-infrared absorbing dyecontaining a squarylium-based compound (A) and at least one compound (B)selected from the group consisting of a phthalocyanine-based compound(B-1) and a cyanine-based compound (B-2).

[2] The optical filter as stated in the item [1], wherein the absorptionmaximum of the squarylium-based compound (A) is present on the side ofshorter wavelength than the absorption maximum of the compound (B).

[3] The optical filter as stated in the item [2], wherein thesquarylium-based compound (A) has an absorption maximum in thewavelength region of not less than 600 nm but less than 800 nm, and thecompound (B) has an absorption maximum in the wavelength region of morethan 600 nm but not more than 800 nm.

[4] The optical filter as stated in any one of the items [1] to [3],wherein when the amount of the whole near-infrared absorbing dye is 100%by weight, the content of the squarylium-based compound (A) is 20 to 95%by weight, and the content of the compound (B) is 5 to 80% by weight.

[5] The optical filter as stated in any one of the items [1] to [4],wherein the squarylium-based compound (A) is a compound represented bythe following formula (I) or (II):

wherein R^(a), R^(b) and Y satisfy the following condition (i) or (ii):

(i) plural R^(a) are each independently a hydrogen atom, a halogen atom,a sulfo group, a hydroxyl group, a cyano group, a nitro group, acarboxyl group, a phosphoric acid group, -L¹ or a —NR^(e)R^(f) group(R^(e) and R^(f) are each independently a hydrogen atom, -L^(a), -L^(b),-L^(c), -L^(d) or -L^(e)),

plural R^(b) are each independently a hydrogen atom, a halogen atom, asulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxylgroup, a phosphoric acid group, -L¹ or a —NR^(g)R^(h) group (R^(g) andR^(h) are each independently a hydrogen atom, -L^(a), -L^(b), -L^(c),-L^(d), -L^(e) or a —C(O)R^(i) group (R^(i) is -L^(a), -L^(b), -L^(c),-L^(d) or L^(e))),

plural Y are each independently a —NR^(j)R^(k) group (R^(j) and R^(k)are each independently a hydrogen atom, -L^(a), -L^(b), -L^(c), -L^(d)or -L^(e)),

L¹ is

(L^(a)) an aliphatic hydrocarbon group of 1 to 9 carbon atoms, which mayhave a substituent L,

(L^(b)) a halogen-substituted alkyl group of 1 to 9 carbon atoms, whichmay have a substituent L,

(L^(c)) an alicyclic hydrocarbon group of 3 to 14 carbon atoms, whichmay have a substituent L,

(L^(d)) an aromatic hydrocarbon group of 6 to 14 carbon atoms, which mayhave a substituent L,

(L^(e)) a heterocyclic group of 3 to 14 carbon atoms, which may have asubstituent L,

(L^(f)) an alkoxy group of 1 to 9 carbon atoms, which may have asubstituent L,

(L^(g)) an acyl group of 1 to 9 carbon atoms, which may have asubstituent L, or

(L^(h)) an alkoxycarbonyl group of 1 to 9 carbon atoms, which may have asubstituent L,

the substituent L is at least one kind selected from the groupconsisting of an aliphatic hydrocarbon group of 1 to 9 carbon atoms, ahalogen-substituted alkyl group of 1 to 9 carbon atoms, an alicyclichydrocarbon group of 3 to 14 carbon atoms, an aromatic hydrocarbon groupof 6 to 14 carbon atoms and a heterocyclic group of 3 to 14 carbonatoms, and the above L^(a) to L^(b) may further have at least one atomor group selected from the group consisting of a halogen atom, a sulfogroup, a hydroxyl group, a cyano group, a nitro group, a carboxyl group,a phosphoric acid group and an amino group;

(ii) at least one of two R^(a) on one benzene ring and Y on the samebenzene ring are bonded to each other to form a heterocyclic ring of 5or 6 constituent atoms containing at least one nitrogen atom, and theheterocyclic ring may have a substituent, and

R^(b) and R^(a) which does not take part in the formation of theheterocyclic ring have the same meanings as those of R^(b) and R^(a) inthe condition (i), respectively;

wherein X is O, S, Se, N—R^(c) or C—R^(d)R^(d),

plural R^(c) are each independently a hydrogen atom, -L^(a), -L^(b),-L^(c), -L^(d) or -L^(e),

plural R^(d) are each independently a hydrogen atom, a halogen atom, asulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxylgroup, a phosphoric acid group, -L¹ or a —NR^(e)R^(f) group, andneighboring R^(d) and R^(d) may be bonded to each other to form a ringwhich may have a substituent, and

L^(a) to L^(e), L¹, R^(e) and R^(f) have the same meanings as those ofL^(a) to L^(e), L¹, R^(e) and R^(f) defined in the formula (I).

[6] The optical filter as stated in any one of the items [1] to [5],wherein the phthalocyanine-based compound (B-1) is a compoundrepresented by the following formula (III):

wherein M represents two hydrogen atoms, two monovalent metal atoms, adivalent metal atom, or substituted metal atoms containing a trivalentor tetravalent metal atom,

plural R_(a), R_(b), R_(c) and R_(d) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group,an amino group, an amide group, an imide group, a cyano group, a silylgroup, -L¹, —S-L², —SS-L², —SO₂-L³ or —N═N-L⁴, or at least onecombination of R_(a) and R_(b), R_(b) and R_(c), and R_(c) and R_(d) isbonded to form at least one group selected from the group consisting ofgroups represented by the following formulas (A) to (H), and at leastone of R_(a), R_(b), R_(c) and R_(d) bonded to the same aromatic ring isnot a hydrogen atom,

the amino group, the amide group, the imide group and the silyl groupmay have a substituent L defined in the formula (I) as stated in theitem [5],

L¹ has the same meaning as that of L¹ defined in the formula (I),

L² is a hydrogen atom or any one of L^(a) to L^(e) defined in theformula (I),

L³ is a hydroxyl group or any one of the above L^(a) to L^(e), and

L⁴ is any one of the above L^(a) to L^(e);

wherein a combination of R_(x) and R_(y) is a combination of R_(a) andR_(b), R_(b) and R_(c), or R_(c) and R_(d), and

plural R_(A) to R_(L) are each independently a hydrogen atom, a halogenatom, a hydroxyl group, a nitro group, an amino group, an amide group,an imide group, a cyano group, a silyl group, -L¹, —S-L², —SS-L²,—SO₂-L³ or —N═N-L⁴ (L¹ to L⁴ have the same meanings as those of L¹ to L⁴defined in the formula (III)), and the amino group, the amide group, theimide group and the silyl group may have the substituent L.

[7] The optical filter as stated in the item [6], wherein M in theformula (III) is a divalent transition metal, a halide of a trivalent ortetravalent metal or an oxide of a tetravalent metal, each of saidmetals belonging to the periodic table Group 5 to Group 11 and belongingto the periodic table Period 4 to Period 5.

[8] The optical filter as stated in any one of the items [1] to [7],wherein the cyanine-based compound (B-2) is a compound represented byany one of the following formulas (IV-1) to (IV-3):

wherein X_(a) ⁻ is a monovalent anion,

plural D are each independently a carbon atom, a nitrogen atom, anoxygen atom or a sulfur atom,

plural R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h) and R_(i)are each independently a hydrogen atom, a halogen atom, a hydroxylgroup, a carboxyl group, a nitro group, an amino group, an amide group,an imide group, a cyano group, a silyl group, -L¹-, —S-L², —SS-L²,—SO₂-L³ or —N═N-L⁴, or at least one combination of R_(b) and R_(c),R_(d) and R_(e), R_(e) and R_(f), R_(f) the R_(g), R_(g) and R_(h), andR_(h) and R_(i) is bonded to form at least one group selected from thegroup consisting of groups represented by the following formulas (A) to(H),

the amino group, the amide group, the imide group and the silyl groupmay have a substituent L defined in the formula (I) as stated in theitem [5],

L¹ has the same meaning as that of L¹ defined in the formula (I),

L² is a hydrogen atom or any one of L^(a) to L^(e) defined in theformula (I),

L³ is a hydrogen atom or any one of the above L^(a) to L^(e),

L⁴ is any one of the above L^(a) to L^(e), and

Z_(a) to Z_(d) and Y_(a) to Y_(d) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group,an amino group, an amide group, an imide group, a cyano group, a silylgroup, -L¹, —S-L², —SS-L², —SO₂-L³ or —N═N-L⁴ (L¹ to L⁴ have the samemeanings as those of L¹ to L⁴ in the above R_(a) to R_(i)), orneighboring two Z or neighboring two Y are bonded to each other to forman alicyclic hydrocarbon group of 5- to 6-membered ring, which maycontain at least one of a nitrogen atom, an oxygen atom and a sulfuratom, or neighboring two Z or neighboring two Y are bonded to each otherto form an aromatic hydrocarbon group of 6 to 14 carbon atoms, orneighboring two Z or neighboring two Y are bonded to each other to forma heteroaromatic hydrocarbon group of 3 to 14 carbon atoms, whichcontains at least one of a nitrogen atom, an oxygen atom and a sulfuratom, and these alicyclic hydrocarbon group, aromatic hydrocarbon groupand heteroaromatic hydrocarbon group may have an aliphatic hydrocarbongroup of 1 to 9 carbon atoms or a halogen atom;

wherein a combination of R_(x) and R_(y) is a combination of R_(b) andR_(c), R_(d) and R_(e), R_(e) and R_(f), R_(f) and R_(g), R_(g) andR_(h), or R_(h) and R_(i), and

plural R_(A) to R_(L) are each independently a hydrogen atom, a halogenatom, a hydroxyl group, a carboxyl group, a nitro group, an amino group,an amide group, an imide group, a cyano group, a silyl group, -L¹,—S-L², —SS-L², —SO₂-L³ or —N═N-L⁴ (L¹ to L⁴ have the same meanings asthose of L¹ to L⁴ defined in the formulas (IV-1) to (IV-3)), and theamino group, the amide group, the imide group and the silyl group mayhave the substituent L.

[9] The optical filter as stated in any one of the items [1] to [8],which has a resin substrate containing the near-infrared absorbing dyeand a resin.

[10] The optical filter as stated in the item [9], wherein the contentof the whole near-infrared absorbing dye is 0.01 to 5.0 parts by weightbased on 100 parts by weight of the resin.

[11] The optical filter as stated in the item [9] or [10], wherein theresin is at least one resin selected from the group consisting of acyclic polyolefin-based resin, an aromatic polyether-based resin, apolyimide-based resin, a fluorene polycarbonate-based resin, a fluorenepolyester-based resin, a polycarbonate-based resin, a polyamide-basedresin, a polyarylate-based resin, a polysulfone-based resin, a polyethersulfone-based resin, a polyparaphenylene-based resin, apolyamidoimide-based resin, a polyethylene naphthalate-based resin, afluorinated aromatic polymer-based resin, a (modified) acrylic resin, anepoxy-based resin, an allyl ester-based curing type resin and asilsesquioxane-based ultraviolet curing resin.

[12] An optical filter containing a squarylium-based compound (A) and acompound which absorbs fluorescence of the squarylium-based compound(A).

[13] The optical filter as stated in any one of the items [1] to [12],which further contains at least one near-ultraviolet absorbing agentselected from the group consisting of an azomethine-based compound, anindole-based compound, a benzotriazole-based compound and atriazine-based compound.

[14] The optical filter as stated in any one of the items [1] to [13],which is for a solid-state image pickup device.

[15] A solid-state image pickup device equipped with the optical filteras stated in any one of the items [1] to [13].

[16] A camera module equipped with the optical filter as stated in anyone of the items [1] to [13].

Effect of the Invention

According to the present invention, an optical filter which generateslittle scattered light during light absorption and is excellent intransmittance property can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a sectional schematic view showing an example of aconventional camera module. FIG. 1B is a sectional schematic viewshowing an example of a camera module using an optical filter 6′ of thepresent invention.

FIG. 2 is a schematic view showing a method for measuring atransmittance in the case where the transmittance is measured in theperpendicular direction to an optical filter.

FIG. 3 is a schematic view showing a method for measuring atransmittance in the case where the transmittance is measured at anangle of 30° to the perpendicular direction to an optical filter.

FIG. 4 is a schematic view showing a method for measuring an intensityof scattered light.

EMBODIMENT FOR CARRYING OUT THE INVENTION

The present invention is specifically described hereinafter.

The optical filter of the present invention contains a squarylium-basedcompound (A) and a compound which absorbs or quenches fluorescence ofthe squarylium-based compound (A). Specifically, the optical filter ofthe present invention contains a near-infrared absorbing dye containinga squarylium-based compound (A) and at least one compound (B) selectedfrom the group consisting of a phthalocyanine-based compound (B-1) and acyanine-based compound (B-2), and the optical filter preferably has aresin substrate containing the near-infrared absorbing dye and a resin.Further, the optical filter of the present invention may have anear-infrared reflecting film.

[Resin Substrate]

The resin substrate may be a single layer substrate or a multilayersubstrate, and contains, as near-infrared absorbing dyes, asquarylium-based compound (A) and at least one compound (B) selectedfrom a phthalocyanine-based compound (B-1) and a cyanine-based compound(B-2). The resin substrate desirably has an absorption maximum in thewavelength range of 600 to 800 nm. When the absorption maximumwavelength of the substrate is in such a range, the substrate can cutnear-infrared rays selectively and efficiently.

When such a resin substrate is used for an optical filter such as anear-infrared cut filter, an absolute value of a difference between awavelength value (Xa) at which the transmittance measured in theperpendicular direction to the optical filer becomes 50% in thewavelength range of 560 to 800 nm and a wavelength value (Xb) at whichthe transmittance measured at an angle of 30° to the perpendiculardirection to the optical filter becomes 50% in the same wavelength rangebecomes small, and an optical filter having a small dependence of theabsorption wavelength on the angle of incidence and having a wideviewing angle can be obtained. The absolute value of a differencebetween (Xa) and (Xb) is preferably less than 20 nm, more preferablyless than 15 nm, particularly preferably less than 10 nm.

Depending upon the intended use of a camera module, the meantransmittance of a resin substrate containing the squarylium-basedcompound (A) and the compound (B) and having a thickness of 100 μmsometimes needs to be not less than 50%, preferably not less than 65%,in the so-called visible region of a wavelength of 400 to 700 nm.

The thickness of the resin substrate can be properly selected accordingto the desired use and is not specifically restricted. However, thethickness is preferably adjusted so that the substrate may have suchimprovement in the incident angle dependence as previously mentioned,and it is more preferably 30 to 250 μm, still more preferably 40 to 200μm, particularly preferably 50 to 150 μm.

When the thickness of the resin substrate is in the above range, theoptical filter using the substrate can be reduced in size and weight, sothat it can be preferably applied to various uses such as a solid-stateimage pickup device. Especially when the resin substrate is used for alens unit of a camera module or the like, lowering of height of the lensunit can be realized, so that such use is preferable.

The resin substrate can further contain at least one near-ultravioletabsorbing agent selected from the group consisting of anazomethine-based compound, an indole-based compound, abenzotriazole-based compound and a triazine-based compound, in additionto the near-infrared absorbing dye containing the squarylium-basedcompound (A) and the compound (B). By the use of such a resin substrate,an optical filter having a small dependence on the incident angle evenin the near-ultraviolet wavelength region and having a wide viewingangle can be obtained.

The near-infrared absorbing dye and the near-ultraviolet absorbing agentmay be contained in the same layer or may be contained in differentlayers. When they are contained in the same layer, there can bementioned, for example, an embodiment wherein the near-infraredabsorbing dye and the near-ultraviolet absorbing agent are bothcontained in the same resin substrate. When they are contained indifferent layers, there can be mentioned, for example, an embodimentwherein a layer containing the near-ultraviolet absorbing agent islaminated on a resin substrate containing the near-infrared absorbingdye.

The near-infrared absorbing dye and the near-ultraviolet absorbing agentare more preferably contained in the same layer, and in such a case,control of the content ratio between the near-infrared absorbing dye andthe near-ultraviolet absorbing agent can be made more easily than in thecase where they are contained in different layers.

<Near-Infrared Absorbing Dye>

(1) Squarylium-Based Compound (A)

The squarylium-based compound (A) is preferably a compound representedby the following formula (I) (also referred to as a “compound (I)”hereinafter) or a compound represented by the following formula (II)(also referred to as a “compound (II)” hereinafter).

In the formula (I), R^(a), R^(b) and Y satisfy the following condition(i) or (ii).

(i) Plural R^(a) are each independently a hydrogen atom, a halogen atom,a sulfo group, a hydroxyl group, a cyano group, a nitro group, acarboxyl group, a phosphoric acid group, -L¹ or a —NR^(e)R^(f) group(R^(e) and R^(f) are each independently a hydrogen atom, -L^(a), -L^(b),-L^(c), -L^(d) or L^(e)),

plural R^(b) are each independently a hydrogen atom, a halogen atom, asulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxylgroup, a phosphoric acid group, -L¹ or a —NR^(g)R^(h) group (R^(g) andR^(h) are each independently a hydrogen atom, -L^(a), -L^(b), -L^(c),-L^(d), -L^(e) or a —C(O)R^(i) group (R¹ is -L^(a), -L^(b), -L^(c),-L^(d) or -L^(e))),

plural Y are each independently a —NR^(j)R^(k) group (R^(j) and R^(k)are each independently a hydrogen atom, -L^(a), -L^(b), -L^(c), -L^(d)or -L^(e)),

L¹ is

(L^(a)) an aliphatic hydrocarbon group of 1 to 9 carbon atoms, which mayhave a substituent L,

(L^(b)) a halogen-substituted alkyl group of 1 to 9 carbon atoms, whichmay have a substituent L,

(L^(c)) an alicyclic hydrocarbon group of 3 to 14 carbon atoms, whichmay have a substituent L,

(L^(d)) an aromatic hydrocarbon group of 6 to 14 carbon atoms, which mayhave a substituent L,

(L^(e)) a heterocyclic group of 3 to 14 carbon atoms, which may have asubstituent L,

(L^(f)) an alkoxy group of 1 to 9 carbon atoms, which may have asubstituent L,

(L^(g)) an acyl group of 1 to 9 carbon atoms, which may have asubstituent L, or

(L^(h)) an alkoxycarbonyl group of 1 to 9 carbon atoms, which may have asubstituent L,

the substituent L is at least one kind selected from the groupconsisting of an aliphatic hydrocarbon group of 1 to 9 carbon atoms, ahalogen-substituted alkyl group of 1 to 9 carbon atoms, an alicyclichydrocarbon group of 3 to 14 carbon atoms, an aromatic hydrocarbon groupof 6 to 14 carbon atoms and a heterocyclic group of 3 to 14 carbonatoms, and the above L^(a) to L^(b) may further have at least one atomor group selected from the group consisting of a halogen atom, a sulfogroup, a hydroxyl group, a cyano group, a nitro group, a carboxyl group,a phosphoric acid group and an amino group. The total number of carbonatoms of each of L^(a) to L^(h) including a substituent is preferably 50or less, more preferably 40 or less, particularly preferably 30 or less.When the number of carbon atoms is larger than the upper limit of thisrange, synthesis of a dye sometime becomes difficult, and the absorptionintensity per unit weight tends to be lowered.

(ii) At least one of two R^(a) on one benzene ring and Y on the samebenzene ring are bonded to each other to form a heterocyclic ring of 5or 6 constituent atoms containing at least one nitrogen atom, and theheterocyclic ring may have a substituent, and

R^(b) and R^(a) which does not take part in the formation of theheterocyclic ring have the same meanings as those of R^(b) and R^(a) inthe condition (i), respectively.

Examples of the aliphatic hydrocarbon groups of 1 to 9 carbon atoms inthe above L^(a) and L include alkyl groups, such as methyl group (Me),ethyl group (Et), n-propyl group (n-Pr), isopropyl group (i-Pr), n-butylgroup (n-Bu), sec-butyl group (s-Bu), tert-butyl group (t-Bu), pentylgroup, hexyl group, octyl group and nonyl group; alkenyl groups, such asvinyl group, 1-propenyl group, 2-propenyl group, butenyl group,1,3-butadienyl group, 2-methyl-1-propenyl group, 2-pentenyl group,hexenyl group and octenyl group; and alkynyl groups, such as ethynylgroup, propynyl group, butynyl group, 2-methyl-1-propynyl group, hexynylgroup and octynyl group.

Examples of the halogen-substituted alkyl groups of 1 to 9 carbon atomsin the above L^(b) and L include trichloromethyl group, trifluoromethylgroup, 1,1-dichloroethyl group, pentachloroethyl group, pentafluoroethylgroup, heptachloropropyl group and heptafluoropropyl group.

Examples of the alicyclic hydrocarbon groups of 3 to 14 carbon atoms inthe above L^(c) and L include cycloalkyl groups, such as cyclobutylgroup, cyclopentyl group, cyclohexyl group, cycloheptyl group,cyclooctyl group, norbornane group and adamantane group.

Examples of the aromatic hydrocarbon groups of 6 to 14 carbon atoms inthe above L^(d) and L include phenyl group, tolyl group, xylyl group,mesytyl group, cumenyl group, 1-naphthyl group, 2-naphthyl group,anthracenyl group, phenanthryl group, acenaphthyl group, phenalenylgroup, tetrahydronaphthyl group, indanyl group and biphenylyl group.

Examples of the heterocyclic groups of 3 to 14 carbon atoms in the aboveL^(e) and L include groups composed of heterocyclic rings such as furan,thiophene, pyrrole, pyrazole, imidazole, triazole, oxazole, oxadiazole,thiazole, thiadiazole, indole, indoline, indolenine, benzofuran,benzothiophene, carbazole, dibenzofuran, dibenzothiophene, pyridine,pyrimidine, pyrazine, pyridazine, quinoline, isoquinoline, acridine andphenazine.

Examples of the alkoxy groups of 1 to 9 carbon atoms in the above L^(f)include methoxy group, ethoxy group, propoxy group, isopropoxy group,butoxy group, 2-methoxyethoxy group, pentyloxy group, hexyloxy group,octyloxy group, methoxymethyl group, methoxyethyl group, methoxypropylgroup, methoxybutyl group, methoxyhexyl group, ethoxyethyl group,ethoxyethyl group, ethoxypropyl group, ethoxybutyl group, ethoxyhexylgroup, propoxymethyl group, propoxypropyl group, propoxyhexyl group andbutoxyethyl group.

Examples of the acyl groups of 1 to 9 carbon atoms in the above L^(g)include acetyl group, propionyl group, butyryl group, isobutyryl group,valeryl group, isovaleryl group and benzoyl group.

Examples of the alkoxycarbonyl groups of 1 to 9 carbon atoms in theabove L^(h) include methoxycarbonyl group, ethoxycarbonyl group,propoxycarbonyl group, isopropoxycarbonyl group, butoxycarbonyl group,2-methoxyethoxycarbonyl group, pentyloxycarbonyl group, hexyloxycarbonylgroup and octyloxycarbonyl group.

As the L^(a), the aforesaid “aliphatic hydrocarbon groups of 1 to 9carbon atoms” and the aliphatic hydrocarbon groups further having thesubstituent L can be mentioned. Of these, preferred are methyl group,ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butylgroup, tert-butyl group, pentyl group, hexyl group, octyl group,4-phenylbutyl group and 2-cyclohexylethyl, and more preferred are methylgroup, ethyl group, n-propyl group, isopropyl group, n-butyl group,sec-butyl group and tert-butyl group.

As the L^(b), the aforesaid “halogen-substituted alkyl groups of 1 to 9carbon atoms” and the halogen-substituted alkyl groups further havingthe substituent L can be mentioned. Of these, preferred aretrichloromethyl group, pentachloroethyl group, trifluoromethyl group,pentafluoroethyl group, 5-cyclohexyl-2,2,3,3-tetrafluoropentyl group and2,2-dichloro-4-phenoxybutyl group, and more preferred aretrichloromethyl group, pentachloroethyl group, trifluoromethyl group andpentafluoroethyl group.

As the L^(c), the aforesaid “alicyclic hydrocarbon groups of 3 to 14carbon atoms” and the alicyclic hydrocarbon groups further having thesubstituent L can be mentioned. Of these, preferred are cyclobutylgroup, cyclopentyl group, cyclohexyl group, 4-ethylcyclohexyl group,cyclooctyl group and 4-phenylcycloheptyl group, and more preferred arecyclopentyl group, cyclohexyl group and 4-ethylcyclohexyl group.

As the L^(d), the aforesaid “aromatic hydrocarbon groups of 6 to 14carbon atoms” and the aromatic hydrocarbon groups further having thesubstituent L can be mentioned. Of these, preferred are phenyl group,1-naphthyl group, 2-naphthyl group, tolyl group, xylyl group, mesytylgroup, cumenyl group, 3,5-di-tert-butylphenyl group, 4-cyclopentylphenylgroup, 2,3,6-triphenylphenyl group, 2,3,4,5,6-pentaphenylphenyl groupand 4-α-cumylphenoxy group, and more preferred are phenyl group, tolylgroup, xylyl group, mesytyl group, cumenyl group,2,3,4,5,6-pentaphenylphenyl group and 4-α-cumylphyenoxy group.

As the L^(e), the aforesaid “heterocyclic groups of 3 to 14 carbonatoms” and the heterocyclic groups further having the substituent L canbe mentioned. Of these, preferred are groups composed of furan,thiophene, pyrrole, indole, indoline, indolenine, benzofuran andbenzothiophene, and more preferred are groups composed of furan,thiophene and pyrrole.

As the L^(f), the aforesaid “alkoxy groups of 1 to 9 carbon atoms” andthe alkoxy groups further having the substituent L can be mentioned. Ofthese, preferred are methoxy group, ethoxy group, propoxy group,isopropoxy group, butoxy group, 2-methoxyethoxy group, methoxymethylgroup, methoxyethyl group, 2-phenylethoxy group, 3-cyclohexylpropoxygroup, pentyloxy group, hexyloxy group and octyloxy group, and morepreferred are methoxy group, ethoxy group, propoxy group, isopropoxygroup and butoxy group.

As the L^(g), the aforesaid “acyl groups of 1 to 9 carbon atoms” and theacyl groups further having the substituent L can be mentioned. Of these,preferred are acetyl group, propionyl group, butyryl group, isobutyrylgroup, benzoyl group and 4-propylbenzoyl group, and more preferred areacetyl group, propionyl group and benzoyl group.

As the L^(h), the aforesaid “alkoxycarbonyl groups of 1 to 9 carbonatoms” and the alkoxycarbonyl groups further having the substituent Lcan be mentioned. Of these, preferred are methoxycarbonyl group,ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group,butoxycarbonyl group, 2-trifluoromethylethoxycarbonyl group and2-phenylethoxycarbonyl group, and more preferred are methoxycarbonylgroup and ethoxycarbonyl group.

The L^(a) to L^(h) may further have at least one atom or group selectedfrom the group consisting of a halogen atom, a sulfo group, a hydroxylgroup, a cyano group, a nitro group, a carboxyl group, a phosphoric acidgroup and an amino group. Examples thereof include 4-sulfobutyl group,4-cyanobutyl group, 5-carboxypentyl group, 5-aminopentyl group,3-hydroxypropyl group, 2-phosphorylethyl group,6-amino-2,2-dichlorohexyl group, 2-chloro-4-hdyroxybutyl group,2-cyanocyclobutyl group, 3-hydroxycyclopentyl group,3-carboxycyclopentyl group, 4-aminocyclohexyl group, 4-hydroxycyclohexylgroup, 4-hydroxyphenyl group, pentafluorophenyl group, 2-hydroxynaphthylgroup, 4-aminophenyl group, 2,3,4,5,6-pentafluorophenyl group,4-nitrophenyl group, group composed of 3-methylpyrrole, 2-hydroxyethoxygroup, 3-cyanopropoxy group, 4-fluorobenzoyl group,2-hydroxyethoxycarbonyl group and 4-cyanobutoxycarbonyl group.

The R^(a) in the above condition (i) is preferably a hydrogen atom, achlorine atom, a fluorine atom, a methyl group, an ethyl group, an-propyl group, an isopropyl group, a hydroxyl group, a n-butyl group, asec-butyl group, a tert-butyl group, a cyclohexyl group, a phenyl group,an amino group, a dimethylamino group or a nitro group, and is morepreferably a hydrogen atom, a chlorine atom, a fluorine atom, a methylgroup, an ethyl group, a n-propyl group, an isopropyl group or ahydroxyl group.

The R^(b) is preferably a hydrogen atom, a chlorine atom, a fluorineatom, a methyl group, an ethyl group, a n-propyl group, an isopropylgroup, a n-butyl group, a sec-butyl group, a tert-butyl group, acyclohexyl group, a phenyl group, an amino group, a dimethylamino group,a cyano group, a nitro group, a hydroxyl group, an acetylamino group, apropionylamino group, a N-methylacetylamino group, atrifluoromethanoylamino group, a pentafluoroethanoylamino group, at-butanoylamino group or a cyclohexanoylamino group, and is morepreferably a hydrogen atom, a chlorine atom, a fluorine atom, a methylgroup, an ethyl group, a n-propyl group, an isopropyl group, adimethylamino group, a nitro group, a hydroxyl group, an acetylaminogroup, a propionylamino group, a trifluoromethanoylamino group, apentafluoroethanoylamino group, a t-butanoylamino group or acyclohexanoylamino group.

The Y is preferably an amino group, a methylamino group, a dimethylaminogroup, a diethylamino group, a di-n-propylamino group, adiisopropylamino group, a di-n-butylamino group, a di-t-butylaminogroup, a N-ethyl-N-methylamino group or a N-cyclohexyl-N-methylaminogroup, and is more preferably a dimethylamino group, a diethylaminogroup, a di-n-propylamino group, a diisopropylamino group, adi-n-butylamino group or a di-t-butylamino group.

Examples of the heterocyclic rings of 5 or 6 constituent atomscontaining at least one nitrogen atom, which are formed by bonding of atleast one of two R^(a) on one benzene ring and Y on the same benzenering to each other, in the condition (ii) of the aforesaid formula (I)include pyrrolidine, pyrrole, imidazole, pyrazole, piperidine, pyridine,piperazine, pyridazine, pyrimidine and pyrazine. Of these heterocyclicrings, preferred are heterocyclic rings wherein one atom adjacent to acarbon atom that constitutes the heterocyclic ring and constitutes thebenzene ring is a nitrogen atom, and more preferred is pyrrolidine.

In the formula (II), X is O, S, Se, N—R^(c) or C—R^(d)R^(d),

plural R^(d) are each independently a hydrogen atom, -L^(a), -L^(b),-L^(c), -L^(d) or -L^(e),

plural R^(d) are each independently a hydrogen atom, a halogen atom, asulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxylgroup, a phosphoric acid group, -L¹ or a —NR^(e)R^(f) group, andneighboring R^(d) and R^(d) may be bonded to each other to form a ringwhich may have a substituent, and

L^(a) to L^(e), L¹, R^(e) and R^(f) have the same meanings as those ofL^(a) to L^(e), L¹, R^(e) and R^(f) defined in the formula (I).

R^(c) in the formula (II) is preferably a hydrogen atom, a methyl group,an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, asec-butyl group, a tert-butyl group, a n-pentyl group, a n-hexyl group,a cyclohexyl group, a phenyl group, a trifluoromethyl group or apentafluoroethyl group, and is more preferably a hydrogen atom, a methylgroup, an ethyl group, a n-propyl group or an isopropyl group.

R^(d) in the formula (II) is preferably a hydrogen atom, a chlorineatom, a fluorine atom, a methyl group, an ethyl group, a n-propyl group,an isopropyl group, a n-butyl group, a sec-butyl group, a tert-butylgroup, a n-pentyl group, a n-hexyl group, a cyclohexyl group, a phenylgroup, a methoxy group, a trifluoromethyl group, a pentafluoroethylgroup or a 4-aminocyclohexyl group, and is more preferably a hydrogenatom, a chlorine atom, a fluorine atom, a methyl group, an ethyl group,a n-propyl group, an isopropyl group, a trifluoromethyl group or apentafluoroethyl group.

The above X is preferably O, S, Se, N-Me, N-Et, CH₂, C-Me₂ or C-Et₂, andis more preferably S, C-Me₂ or C-Et₂.

In the formula (II), neighboring R^(d) and R^(d) may be bonded to eachother to form a ring. Examples of such rings include benzoindoleninering, α-naphthoimidazole ring, β-naphthoimidazole ring, α-naphthooxazolering, β-naphthooxazole ring, α-naphthothiazole ring, β-naphthothiazolering, α-naphthoselenazole ring and β-naphthoselenazole ring.

Structures of the compound (I) and the compound (II) can be representedalso by such descriptive means as have resonance structures, such as thefollowing formula (I-2) and the following formula (II-2), in addition tothe descriptive means such as the following formula (I-1) and thefollowing formula (II-1). That is to say, a difference between thefollowing formula (I-1) and the following formula (I-2) and a differencebetween the following formula (II-1) and the following formula (II-2)are only descriptive means for the structures, and both of themrepresent the same compound. In the present invention, the structures ofthe squarylium-based compounds are represented by descriptive means suchas the following formula (I-1) and the following formula (II-1) unlessotherwise noted.

The structures of the compound (I) and the compound (II) are notspecifically restricted provided that the compound (I) and the compound(II) satisfy the requirements of the formula (I) and the formula (II),respectively, and for example, when the structures of them arerepresented by the formula (I-1) and the formula (II-1), thesubstituents which are bonded to the central 4-membered ring and are onthe right-hand side and the left-hand side thereof may be the same ordifferent, but they are preferably the same as each other because ofease of synthesis. For example, the compound represented by thefollowing formula (I-3) and the compound represented by the followingformula (I-4) can be regarded as identical with each other.

Specific examples of the compounds (I) and the compounds (II) includecompounds (a-1) to (a-36) described in the following Table 1 to 3, whichhave basic skeletons represented by the following (I-A) to (I-H).

TABLE 1 Basic Substituent Compound skeleton R^(a1) R^(a2) R^(b1) R^(b2)R^(g) R^(h) R^(j1) R^(k1) R^(k2) R^(k3) R^(k4) (a-1) (I-A) H H Me H — —Et n-Pr — — — (a-2) H H OH H — — n-Bu n-Bu — — — (a-3) Me H OH H — —t-Bu t-Bu — — — (a-4) (I-B) H H H — Me Me n-Pr n-Pr — — — (a-5) H H H —H

Et Et — — — (a-6) H H H — Me

n-Bu n-Bu — — — (a-7) H H H — H

Me Et — — — (a-8) H H H — H

n-Bu n-Bu — — — (a-9) Me H H — H

i-Pr i-Pr — — — (a-10) (I-C) H — OH H — — Me H H H H (a-11) Me — Me H —— Me Me H Me Me (a-12) H — OH H — — Me Me H Me Me (a-13) H — H H — —n-Bu H H Et H (a-14) H — OH H — —

Me H Me Me (a-15) (I-D) H — H — H H Me H H Me Me (a-16) H — H — H

Me Me H Me Me (a-17) Et — H — H

n-Bu H H H H (a-18) H — H — H

Me Me H Me Me (a-19) Me — H — H

Et Me H Me Me (a-20) H — H — H

Me Me H Me Me

TABLE 2 Substituent Compound Basic skeleton R^(b1) R^(b2) R^(g) R^(h)R^(j1) R^(j2) R^(j3) R^(j4) R^(j5) R^(j6) (a-21) (I-E) OH H — — H H H HH H (a-22) OH H — — H H H H Me Me (a-23) OH H — — Me H Me H Me Me (a-24)OH Me — — H H H H n-Bu n-Bu (a-25) (I-F) H — H

H H H H Me Me (a-26) H — Me

Me H Me H Me Me (a-27) H — H

H H Me Me Et Et (a-28) H — H

H H H H Me Me

TABLE 3 Basic Substituent Compound skeleton X R^(c) R^(d1) R^(d2) R^(d3)R^(d4) R^(d5) R^(d6) (a-29) (I-G) C(CH₃)₂ Et H H H H — — (a-30) CH₂ n-BuH H F H — — (a-31) S Me H Me Me H — — (a-32) O Et H CF₃ CF₃ H — — (a-33)(I-H) C(CH₃)₂ i-Pr H H H H H H (a-34) S n-Bu H H H CF₃ CF₃ H (a-35)C(CH₃)₂ CF₂CF₃ H H H H —OMe H (a-36) C(CH₃)₂ Et H H H Me Me H

It is enough just to synthesize the compound (I) and the compound (II)by generally known processes, and for example, they can be synthesizedreferring to the processes described in Japanese Patent Laid-OpenPublication No. 1989-228960, Japanese Patent Laid-Open Publication No.2001-40234, Japanese Patent No. 3196383, etc.

The absorption maximum wavelength of the squarylium-based compound (A)is preferably not less than 600 nm, more preferably not less than 620nm, particularly preferably not less than 650 nm, and is preferably lessthan 800 nm, more preferably not more than 760 nm, particularlypreferably not more than 740 nm. When the absorption maximum wavelengthis in such a wavelength range, sufficient near-infrared absorptionproperty and visible light transmittance are compatible with each other.

The absorption maximum of the squarylium-based compound (A) ispreferably present in the wavelength region of shorter wavelength thanthe absorption maximum of the compound (B) that is used at the sametime. A difference in the absorption maximum wavelength between thesquarylium-based compound (A) and the compound (B) is preferably 1 to100 nm, more preferably 5 to 80 nm, still more preferably 10 to 60 nm.When the difference in the absorption maximum wavelength is in such arange, fluorescence emitted from the squarylium-based compound (A) canbe more effectively absorbed, and the intensity of scattered light ofthe optical filter can be depressed.

(2) Compound (B)

The compound (B) is at least one compound selected from the groupconsisting of a phthalocyanine-based compound (B-1) and a cyanine-basedcompound (B-2), and both of the phthalocyanine-based compound (B-1) andthe cyanine-based compound (B-2) may be used.

(2-1) Phthalocyanine-Based Compound (B-1)

The phthalocyanine-based compound (B-1) is preferably a compoundrepresented by the following formula (III) (also referred to as a“compound (III)” hereinafter”).

In the formula (III), M represents two hydrogen atoms, two monovalentmetal atoms, a divalent metal atom, or substituted metal atomscontaining a trivalent or tetravalent metal atom.

Plural R_(a), R_(b), R_(c) and R_(d) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group,an amino group, an amide group, an imide group, a cyano group, a silylgroup, -L¹, —S-L², —SS-L², —SO₂-L³ or —N═N-L⁴, or at least onecombination of R_(a) and R_(b), R_(b) and R_(c), and R_(c) and R_(d) isbonded to form at least one group selected from the group consisting ofgroups represented by the following formulas (A) to (H), and at leastone of R_(a), R_(b), R_(c) and R_(d) bonded to the same aromatic ring isnot a hydrogen atom.

The amino group, the amide group, the imide group and the silyl groupmay have a substituent L defined in the aforesaid formula (I),

L¹ has the same meaning as that of L¹ defined in the formula

L² is a hydrogen atom or any one of L^(a) to L^(e) defined in theformula (I),

L³ is a hydroxyl group or any one of the above L^(a) to L^(e), and

L⁴ is any one of the above L^(a) to L^(e).

In the formulas (A) to (H), a combination of R_(x) and R_(y) is acombination of R_(a) and R_(b), R_(b) and R_(c), or R_(c) and R_(d), and

plural R_(A) to R_(L) are each independently a hydrogen atom, a halogenatom, a hydroxyl group, a nitro group, an amino group, an amide group,an imide group, a cyano group, a silyl group, -L¹, —S-L², —SS-L²,—SO₂-L³ or —N═N-L⁴,

the amino group, the amide group, the imide group and the silyl groupmay have the substituent L, and L¹ to L⁴ have the same meanings as thoseof L¹ to L⁴ defined in the formula (III).

Examples of the amino groups which may have a substituent L in the aboveR_(a) to R_(d) and R_(A) to R_(L) include amino group, ethylamino group,dimethylamino group, methylethylamino group, dibutylamino group anddiisopropylamino group.

Examples of the amide groups which may have a substituent L in the aboveR_(a) to R_(d) and R_(A) to R_(L) include amide group, methylamidegroup, dimethylamide group, diethylamide group, dipropylamide group,diisopropylamide group, dibutylamide group, α-lactam group, β-lactamgroup, γ-lactam group and δ-lactam group.

Examples of the imide groups which may have a substituent L in the aboveR_(a) to R_(d) and R_(A) to R_(L) include imide group, methylimidegroup, ethylimide group, diethylimide group, dipropylimide group,diisopropylimide group and dibutylimide group.

Examples of the silyl groups which may have a substituent L in the aboveR_(a) to R_(d) and R_(A) to R_(L) include trimethylsilyl group,tert-butyldimethylsilyl group, triphenylsilyl group and triethylsilylgroup.

Examples of —S-L² in the above R_(a) to R_(d) and R_(A) to R_(L) includethiol group, methyl sulfide group, ethyl sulfide group, propyl sulfidegroup, butyl sulfide group, isobutyl sulfide group, sec-butyl sulfidegroup, tert-butyl sulfide group, phenyl sulfide group,2,6-di-tert-butylphenyl sulfide group, 2,6-diphenylphenyl sulfide groupand 4-cumylphenyl sulfide group.

Examples of —SS-L² in the above R_(a) to R_(d) and R_(A) to R_(L)include disulfide group, methyldisulfide group, ethyl disulfide group,propyl disulfide group, butyl disulfide group, isobutyl disulfide group,sec-butyl disulfide group, tert-butyl disulfide group, phenyl disulfidegroup, 2,6-di-tert-butylphenyl disulfide group, 2,6-diphenylphenyldisulfide group and 4-cumylphenyl disulfide group.

Examples of —SO₂-L² in the above R_(a) to R_(d) and R_(A) to R_(L)include sulfoxyl group, mesyl group, ethylsulfonyl group,n-butylsulfonyl group and p-toluenesulfonyl group.

Examples of —N═N-L⁴ in the above R_(a) to R_(d) and R_(A) to R_(L)include methylazo group, phenylazo group, p-methylphenylazo group andp-dimethylaminophenylazo group.

Examples of the monovalent metal atoms in the above M include Li, Na, K,Rb and Cs.

Examples of the divalent metal atoms in the above M include Be, Mg, Ca,Ba, Ti, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu, Zn, Cd, Hg, Sn and Pb.

Examples of the substituted metal atoms containing a trivalent metalatom in the above M include Al—F, Al—Cl, Al—Br, Al—I, Ga—F, Ga—Cl,Ga—Br, Ga—I, In—F, In—Cl, In—Br, In—I, Tl—F, Tl—Cl, Tl—Br, Tl—I, Fe—Cl,Ru—Cl and Mn—OH.

Examples of the substituted metal atoms containing a tetravalent metalatom in the above M include TiF₂, TiCl₂, TiBr₂, TiI₂, ZrCl₂, HfCl₂,CrCl₂, SiF₂, SiCl₂, SiBr₂, SiI₂, GeF₂, GeCl₂, GeBr₂, GeI₂, SnF₂, SnCl₂,SnBr₂, SnI₂, Zr(OH)₂, Hf(OH)₂, Mn(OH)₂, Si(OH)₂, Ge(OH)₂, Sn(OH)₂, TiR₂,CrR₂, SiR₂, GeR₂, SnR₂, Ti(OR)₂, Cr(OR)₂, Si(OR)₂, Ge(OR)₂, Sn(OR)₂ (Ris an aliphatic group or an aromatic group), TiO, VO and MnO.

As the M, a divalent transition metal, a halide of a trivalent ortetravalent metal or an oxide of a tetravalent metal, each of saidmetals belonging to the periodic table Group 5 to Group 11 and belongingto the periodic table Period 4 to Period 5, is preferable, and of these,Cu, Ni, Co or Vo is particularly preferable because high visible lighttransmittance and stability can be attained.

For synthesizing the phthalocyanine-based compound (B-1), a synthesisprocess by cyclization reaction of such a phthalonitrile derivative asrepresented by the following formula (V) is generally known, but theresulting phthalocyanine-based compound is a mixture of four kinds ofsuch isomers as represented by the following formulas (VI-1) to (VI-4).In the present invention, one kind of an isomer is given as an examplefor one kind of the phthalocyanine-based compound unless otherwisenoted, but other three kinds of isomers can be also used likewise. It ispossible to use these isomers after they are isolated when needed, butin the present invention, they are treated all together as an isomermixture.

Specific examples of the compounds (III) include (b-1) to (b-56)described in the following Tables 4 to 7, which have basic skeletonsrepresented by the following formulas (III-A) to (III-J).

TABLE 4 Basic Substituent Compound skeleton M R_(a1) R_(a2) R_(a3)R_(a4) (b-1) (III-A) Ni —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ —O(CH₂)₂CH₃(b-2) Cu —O(CH₂)₃CH₃ —O(CH₂)₃CH₃ —O(CH₂)₃CH₃ —O(CH₂)₃CH₃ (b-3) VO—O(CH₂)₂CH₃ —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ (b-4) VO

(b-5) Cu

(b-5) Cu

(b-6) VO —S(CH₂)₃CH₃ —S(CH₂)₃CH₃ —S(CH₂)₃CH₃ —S(CH₂)₃CH₃ (b-7) Ni —NH₂—NH₂ —NH₂ —NH₂ (b-8) Cu —NH(CH₂)₃CH₃ —NH(CH₂)₃CH₃ —NH(CH₂)₃CH₃—NH(CH₂)₃CH₃ (b-9) Co —OH —OH —OH —OH (b-10) Cu t-Bu t-Bu t-Bu t-Bu(b-11) VO t-Bu t-Bu t-Bu t-Bu (b-12) VO —C(CF₃)₃ —C(CF₃)₃ —C(CF₃)₃—C(CF₃)₃ (b-13) Cu —O(CF₂)₄CF₃ —O(CF₂)₄CF₃ —O(CF₂)₄CF₃ —O(CF₂)₄CF₃(b-14) Ni

(b-15) Cu

(b-16) Cu

(b-17) VO

(b-18) Ni

(b-19) Cu F

F

(b-20) VO t-Bu —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ (b-21) VO t-Bu—O(CH₂)₂CH₃ t-Bu —O(CH₂)₂CH₃ (b-22) Co —C(CF₃)₃ —S(CH₂)₃CH₃ —S(CH₂)₃CH₃—S(CH₂)₃CH₃

TABLE 5 Basic Substituent Compound skeleton M R_(a1) R_(a2) R_(a3)R_(a4) (b-23) (III-B) Co —NO₂ —NO₂ —NO₂ —NO₂ (b-24) Cu —O(CH₂)₃CH₃—O(CH₂)₃CH₃ —O(CH₂)₃CH₃ —O(CH₂)₃CH₃ (b-25) VO Me Me Me Me (b-26) Cu

(b-27) VO —OH —OH —OH —OH (b-28) Ni F F F F (b-29) Cu Cl Cl Cl Cl (b-30)VO t-Bu —OH t-Bu —OH

TABLE 6 Substituent Compound Basic skeleton M R_(a) R_(b) R_(c) (b-31)(III-C) VO Cl Cl — (b-32) Cu F F — (b-33) Ni —O(CH₂)₃CH₃ —O(CH₂)₃CH₃ —(b-34) VO —OH t-Bu — (b-35) (III-D) Co —OH —OH — (b-36) Ni Et F — (b-37)Cu —O(CH₂)₂CH₃ —O(CH₂)₂CH₃ — (b-38) VO t-Bu t-Bu — (b-39) (III-E) VO MeMe t-Bu (b-40) Cu F F Et (b-41) Co —NO₂ n-Pr n-Pr (b-42) Ni —OH F—O(CH₂)₄CH₃ (b-43) (III-F) VO —O(CH₂)₃CH₃ Me —O(CH₂)₃CH₃ (b-44) VO Ft-Bu F (b-45) Cu Et —NH₂ Et (b-46) Co Cl

Cl

TABLE 7 Basic Substituent Compound skeleton M R_(a) R_(b) R_(c) R_(d)(b-47) (III-G) VO F F F F (b-48) Cu Cl —O(CH₂)₃CH₃ —O(CH₂)₃CH₃ Cl (b-49)VO F t-Bu F F (b-50) Ni —OH n-Pr n-Pr —OH (b-51) (III-H) Cu

Me — (b-52) Cu

Me — (b-53) VO

Me — (b-54) (III-J) VO F t-Bu t-Bu F (b-55) Cu Me Et Et Me (b-56) Cu —OHF —O(CH₂)₃CH₃ —OH

It is enough just to synthesize the compound (III) by a processgenerally known, and for example, the compound can be synthesizedreferring to the processes described in Japanese Patent No. 4081149 and“Phthalocyanine—Chemistry and Functions—” (IPC, 1997).

The absorption maximum wavelength of the phthalocyanine-based compound(B-1) is preferably more than 600 nm, more preferably not less than 640nm, particularly preferably not less than 670 nm, and is preferably notmore than 800 nm, more preferably not more than 780 nm, particularlypreferably not more than 760 nm. When the absorption maximum wave lengthis in such a wavelength range, sufficient near-infrared absorptionproperty and visible light transmittance are compatible with each other.Moreover, fluorescence emitted from the squarylium-based compound (A)can be effectively absorbed, and the intensity of scattered light of theoptical filter can be depressed.

(2-2) Cyanine-Based Compound (B-2)

The cyanine-based compound (B-2) is preferably any one of compoundsrepresented by the following formulas (IV-1) to (IV-3) (also referred toas “compounds (IV-1) to (IV-3)” hereinafter).

In the formulas (IV-1) to (IV-3), X_(a) ⁻ is a monovalent anion,

plural D are each independently a carbon atom, a nitrogen atom, anoxygen atom or a sulfur atom,

plural R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h) and R_(i)are each independently a hydrogen atom, a halogen atom, a hydroxylgroup, a carboxyl group, a nitro group, an amino group, an amide group,an imide group, a cyano group, a silyl group, -L¹, —S-L², —SS-L²,—SO₂-L³ or —N═N-L⁴, or at least one combination of R_(b) and R_(c),R_(d) and R_(e), R_(e) and R_(f), R_(f) the R_(g), R_(g) and R_(h), andR_(h) and R_(i) is bonded to form at least one group selected from thegroup consisting of groups represented by the following formulas (A) to(H),

the amino group, the amide group, the imide group and the silyl groupmay have a substituent L defined in the aforesaid formula (I),

L¹ has the same meaning as that of L¹ defined in the formula (I),

L² is a hydrogen atom or any one of L^(a) to L^(e) defined in theformula (I),

L³ is a hydrogen atom or any one of the above L^(a) to L^(e),

L⁴ is any one of the above L^(a) to L^(e), and

Z_(a) to Z_(d) and Y_(a) to Y_(d) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group,an amino group, an amide group, an imide group, a cyano group, a silylgroup, -L¹, —S-L², —SS-L², —SO₂-L³ or —N═N-L⁴ (L¹ to L⁴ have the samemeanings as those of L¹ to L⁴ in the above R_(a) to R_(i)), orneighboring two Z or neighboring two Y are bonded to each other to forman alicyclic hydrocarbon group of 5- to 6-membered ring, which maycontain at least one of a nitrogen atom, an oxygen atom and a sulfuratom, or neighboring two Z or neighboring two Y are bonded to each otherto form an aromatic hydrocarbon group of 6 to 14 carbon atoms, orneighboring two Z or neighboring two Y are bonded to each other to forma heteroaromatic hydrocarbon group of 3 to 14 carbon atoms, whichcontains at least one of a nitrogen atom, an oxygen atom and a sulfuratom, and these alicyclic hydrocarbon group, aromatic hydrocarbon groupand heteroaromatic hydrocarbon group may have an aliphatic hydrocarbongroup of 1 to 9 carbon atoms or a halogen atom.

In the formulas (A) to (H), a combination of R_(x) and R_(y) is acombination of R_(b) and R_(c), R_(d) and R_(e), R_(e) and R_(f), R_(f)and R_(g), R_(g) and R_(h), or R_(h) and R_(i), and

plural R_(A) to R_(L) are each independently a hydrogen atom, a halogenatom, a hydroxyl group, a carboxyl group, a nitro group, an amino group,an amide group, an imide group, a cyano group, a silyl group, -L¹,—S-L², —SS-L², —SO₂-L³ or —N═N-L⁴ (L¹ to L⁴ have the same meanings asthose of L¹ to L⁴ defined in the formulas (IV-1) to (IV-3)), and theamino group, the amide group, the imide group and the silyl group mayhave the substituent L.

Examples of the alicyclic hydrocarbon groups of 5- to 6-membered ring,which are formed by bonding of Z and Z or Y and Y to each other and maycontain at least one of a nitrogen atom, an oxygen atom and a sulfuratom, in the above Z_(a) to Z_(d) and Y_(a) to Y_(d) include thecompounds given as examples of the alicyclic hydrocarbon groups and theheterocyclic rings in the aforesaid substituent L (except theheteroaromatic hydrocarbon groups).

Examples of the aromatic hydrocarbon groups of 6 to 14 carbon atoms,which are formed by bonding of Z and Z or Y and Y to each other, in theabove Z_(a) to Z_(d) and Y_(a) to Y_(d) include the compounds given asexamples of the aromatic hydrocarbon groups in the aforesaid substituentL.

Examples of the heteroaromatic hydrocarbon groups of 3 to 14 carbonatoms, which are formed by bonding of Z and Z or Y and Y to each other,in the above Z_(a) to Z_(d) and Y_(a) to Y_(d) include the compoundsgiven as examples of the heterocyclic groups in the aforesaidsubstituent L (except the alicyclic hydrocarbon groups containing atleast one of a nitrogen atom, an oxygen atom and a sulfur atom).

Examples of the amino groups which may have a substituent L in the aboveR_(a) to R_(i) and R_(A) to R_(L) include amino group, ethylamino group,dimethylamino group, methylethylamino group, dibutylamino group anddiisopropylamino group.

Examples of the amide groups which may have a substituent L in the aboveR_(a) to R_(i) and R_(A) to R_(L) include amide group, methylamidegroup, dimethylamide group, diethylamide group, dipropylamide group,diisopropylamide group, dibutylamide group, α-lactam group, β-lactamgroup, γ-lactam group and δ-lactam group.

Examples of the imide groups which may have a substituent L in the aboveR_(a) to R_(i) and R_(A) to R_(L) include imide group, methylimidegroup, ethylimide group, diethylimide group, dipropylimide group,diisopropylimide group and dibutylimide group.

Examples of the silyl groups which may have a substituent L in the aboveR_(a) to R_(i) and R_(A) to R_(L) include trimethylsilyl group,tert-butyldimethylsilyl group, triphenylsilyl group and triethylsilylgroup.

Examples of —S-L² in the above R_(a) to R_(i) and R_(A) to R_(L) includethiol group, methyl sulfide group, ethyl sulfide group, propyl sulfidegroup, butyl sulfide group, isobutyl sulfide group, sec-butyl sulfidegroup, tert-butyl sulfide group, phenyl sulfide group,2,6-di-tert-butylphenyl sulfide group, 2,6-diphenylphenyl sulfide groupand 4-cumylphenyl sulfide group.

Examples of —SS-L² in the above R_(a) to R_(i) and R_(A) to R_(L)include disulfide group, methyl disulfide group, ethyl disulfide group,propyl disulfide group, butyl disulfide group, isobutyl disulfide group,sec-butyl disulfide group, tert-butyl disulfide group, phenyl disulfidegroup, 2,6-di-tert-butylphenyl disulfide group, 2,6-diphenylphenyldisulfide group and 4-cumylphenyl disulfide group.

Examples of —SO₂-L³ in the above R_(a) to R_(i) and R_(A) to R_(L)include sulfoxyl group, mesyl group, ethylsulfonyl group,n-butylsulfonyl group and p-toluenesulfonyl group.

Examples of —N═N-L⁴ in the above R_(a) to R_(i) and R_(A) to R_(L)include methylazo group, phenylazo group, p-methylphenylazo group andp-dimethylaminophenylazo group.

Specific examples of the compounds (IV-1) to (IV-3) include (c-1) to(c-19) described in the following Table 8.

TABLE 8 Base Substituent Compound skeleton D R_(a) R_(b) R_(c) R_(d)R_(e) R_(f) R_(g) R_(h) R_(i) Y_(a) Y_(b) Y_(c) Y_(d) Z_(a) Z_(b) Z_(c)X_(a) ⁻ (c-1) (IV-1) C n-Bu Me Me H H H H — — H H H — H H — PF6 (c-2) Cn-Bu Me Me H H H H — — H Cl H — H H — PF6 (c-3) S Et — — H H H H — — H HH — H H — I (c-4) (IV-2) C n-Bu Me Me H H H H — — H H H H H H H PF6(c-5) S Et — — H H H H — — H H H H H H H I (c-6) C n-Bu Me Me H H H H —— H trimethylene H H H H PF6 (c-7) S Et — — H H H H — — H H H Htrimethylene H I (c-8) C n-Bu Me Me H H H H — — H ethylene H H Ph H PF6(c-9) C n-Bu Me Me H H H H — — H ethylene H H diphenylamino H PF6 (c-10)C MeOEt Me Me H H Cl H — — H trimethylene H H Cl H N(SO2CF3)2 (c-11) CMeOEt Me Me H H Cl H — — H H H H H H H N(SO2CF3)2 (c-12) C MeOEt Me Me HH H H — — H trimethylene H H Cl H N(SO2CF3)2 (c-13) S n-Bu — — H H H H —— H trimethylene H H Cl H N(SO2CF3)2 (c-14) C Et Me Me H H H H — — Htrimethylene H H Cl H I (c-15) (IV-3) C 3-methyl-butyl Me Me H H H H H HH H H — H H — PF6 (c-16) C 3-methyl-butyl Me Me H H H H H H H Cl H — H H— PF6 (c-17) C MeOEt Me Me H H H H H H H H H — H H — N(SO2CF3)2 (c-18) C3-methyl-butyl Me Me H H H H H H H H H — trimethylene — PF6 (c-19) C3-methyl-butyl Me Me H H H H H H H Ph H — ethylene — PF6

It is enough just to synthesize the compounds (IV-1) to (IV-3) byprocesses generally known, and for example, the compounds can besynthesized by the process described in Japanese Patent Laid-OpenPublication No. 2009-108267.

The absorption maximum wavelength of the cyanine-based compound (B-2) ispreferably more than 600 nm, more preferably not less than 640 nm,particularly preferably not less than 670 nm, and is preferably not morethan 800 nm, more preferably not more than 780 nm, particularlypreferably not more than 760 nm. When the absorption maximum wavelengthis in such a wavelength range, sufficient near-infrared absorptionproperty and visible light transmittance are compatible with each other.Moreover, fluorescence emitted from the squarylium-based compound (A)can be effectively absorbed, and the intensity of scattered light of theoptical filter can be depressed.

(3) Content Percentage of Squarylium-Based Compound (A) and Compound (B)

When the amount of the whole near-infrared absorbing dye is 100% byweight, the content percentage of the squarylium-based compound (A) ispreferably 20 to 95% by weight, more preferably 25 to 85% by weight,particularly preferably 30 to 80% by weight, and the content percentageof the compound (B) is preferably 5 to 80% by weight, more preferably 10to 70% by weight, particularly preferably 15 to 60% by weight, in thepresent invention. When the content percentages of the squarylium-basedcompound (A) and the compound (B) are in the above ranges, favorablevisible light transmittance, improvement in incident angle dependenceand scattered light reduction effect are compatible with one another.The squarylium-based compound (A) and the compound (B) may be each usedin combination of two or more kinds. In addition to the squarylium-basedcompound (A) and the compound (B), another near-infrared absorbing dyemay be used within limits not detrimental to the effect of the presentinvention, as far as the above content percentages are satisfied.

(4) Content of Near-Infrared Absorbing Dye

In the resin substrate, the content of the near-infrared absorbing dyeis preferably 0.01 to 5.0 parts by weight, more preferably 0.02 to 3.5parts by weight, particularly preferably 0.03 to 2.5 parts by weight,based on 100 parts by weight of the resin used in the production of theresin substrate. When the content of the near-infrared absorbing dye isin the above range, favorable near-infrared absorption property and highvisible light transmittance are compatible each other.

<Resin>

The resin substrate for use in the present invention is not specificallyrestricted provided that it contains a resin and a near-infraredabsorbing dye containing the squarylium-based compound (A) and thecompound (B), but the resin is preferably a transparent resin. Such aresin is not specifically restricted as far as it does not impair theeffect of the present invention. However, in order to ensure heatstability and moldability into a film and in order to produce a filmcapable of forming a dielectric multilayer film through high-temperaturedeposition that is carried out at a deposition temperature of not lowerthan 100° C., there can be mentioned, for example, a resin preferablyhaving a glass transition temperature (Tg) of 110 to 380° C., morepreferably 110 to 370° C., still more preferably 120 to 360° C. When theglass transition temperature of the resin is not lower than 140° C., afilm capable of forming a dielectric multilayer film by deposition at ahigher temperature is obtained, so that such a glass transitiontemperature is particularly preferable.

As the resin, a resin preferably having a total light transmittance (JISK7105) of 75 to 95%, more preferably 78 to 95%, particularly preferably80 to 95%, in a thickness of 0.1 mm can be used. When the total lighttransmittance is in such a range, the resulting substrate exhibitsfavorable transparency as an optical film.

Examples of the resins include a cyclic polyolefin-based resin, anaromatic polyether-based resin, a polyimide-based resin, a fluorenepolycarbonate-based resin, a fluorene polyester-based resin, apolycarbonate-based resin, a polyamide-based (aramid-based) resin, apolyarylate-based resin, a polysulfone-based resin, a polyethersulfone-based resin, a polyparaphenylene-based resin, apolyamidoimide-based resin, a polyethylene naphthalate (PEN)-basedresin, a fluorinated aromatic polymer-based resin, a (modified) acrylicresin, an epoxy-based resin, an allyl ester-based curing type resin anda silsesquioxane-based ultraviolet curing resin.

(1) Cyclic Olefin-Based Resin

The cyclic olefin-based resin is preferably a resin obtained from atleast one monomer selected from the group consisting of a monomerrepresented by the following formula (X₀) and a monomer represented bythe following formula (Y₀), or a resin obtained by further hydrogenatingthe resin thus obtained.

In the formula (X₀), R^(x1) to R^(x4) are each independently an atom ora group selected from the following (i′) to (viii′), and k^(x), m^(x)and p^(x) are each independently 0 or a positive integer.

(i′) a hydrogen atom

(ii′) a halogen atom

(iii′) a trialkylsilyl group

(iv′) a substituted or unsubstituted hydrocarbon group of 1 to 30 carbonatoms, which has a linking group containing an oxygen atom, a sulfuratom, a nitrogen atom or a silicon atom

(v′) a substituted or unsubstituted hydrocarbon group of 1 to 30 carbonatoms

(vi′) a polar group (except (iv′))

(vii′) an alkylidene group formed by bonding of R^(x1) and R^(x2) orR^(x3) and R^(x4) to each other is represented, but R^(x1) to R^(x4)which do not take part in the bonding are each independently an atom ora group selected from the above (i′) to (vi′).

(viii′) a monocyclic or polycyclic hydrocarbon ring or a heterocyclicring formed by bonding of R^(x1) and R^(x2) or R^(x3) and R^(x4) to eachother is represented, but R^(x1) to R^(x4) which do not take part in thebonding are each independently an atom or a group selected from theabove (i′) to (vi′); or a monocyclic hydrocarbon ring or a heterocyclicring formed by bonding of R^(x2) and R^(x3) each other, but R^(x1) toR^(x4) which do not take part in the bonding are each independently anatom or a group selected from the above (i′) to (vi′).

In the formula (Y₀), R^(y1) and R^(y2) are each independently an atom ora group selected from the aforesaid (i′) to (vi′) or represent thefollowing (ix′), and K^(y) and P^(y) are each independently 0 or apositive integer.

(ix′) a monocyclic or polycyclic aliphatic hydrocarbon, an aromatichydrocarbon or a heterocyclic ring, which is formed by bonding of R^(y1)and R^(y2) to each other, is represented.

(2) Aromatic Polyether-Based Resin

The aromatic polyether-based resin preferably has at least onestructural unit selected from the group consisting of a structural unitrepresented by the following formula (1) and a structural unitrepresented by the following formula (2).

In the formula (1), R¹ to R⁴ are each independently a monovalent organicgroup of 1 to 12 carbon atoms, and a to d are each independently aninteger of 0 to 4.

In the formula (2), R¹ to R⁴ and a to d have the same meanings as thoseof R¹ to R⁴ and a to d in the formula (1), respectively, Y is a singlebond, —SO₂— or >C═O, R⁷ and R⁸ are each independently a halogen atom, amonovalent organic group of 1 to 12 carbon atoms or a nitro group, g andh are each independently an integer of 0 to 4, and m is 0 or 1, but whenm is 0, R⁷ is not a cyano group.

Further, the aromatic polyether-based resin preferably has at least onestructural unit selected from the group consisting of a structural unitrepresented by the following formula (3) and a structural unitrepresented by the following formula (4).

In the formula (3), R⁵ to R⁶ are each independently a monovalent organicgroup of 1 to 12 carbon atoms, Z is a single bond, —O—, —S—,—SO₂—, >C═O, —CONH—, —COO— or a divalent organic group of 1 to 12 carbonatoms, e and f are each independently an integer of 0 to 4, and n is 0or 1.

In the formula (4), R⁷, R⁸, Y, m, g and h have the same meanings asthose of R⁷, R⁸, Y, m, g and h in the formula (2), respectively, and R⁵,R⁶, Z, n, e and f have the same meanings as those of R⁵, R⁶, Z, n, e andf in the formula (3), respectively.

(3) Polyimide-Based Resin

The polyimide-based resin is not specifically restricted provided thatit is a high-molecular compound containing an imide linkage in arepeating unit, and it can be synthesized by a process described in, forexample, Japanese Patent Laid-Open Publication No. 2006-199945 orJapanese Patent Laid-Open Publication No. 2008-163107.

(4) Fluorene Polycarbonate-Based Resin

The fluorene polycarbonate-based resin is not specifically restrictedprovided that it is a polycarbonate resin containing a fluorene moiety,and it can be synthesized by a process described in, for example,Japanese Patent Laid-Open Publication No. 2008-163107.

(5) Fluorene Polyester-Based Resin

The fluorene polyester-based resin is not specifically restrictedprovided that it is a polyester resin containing a fluorene moiety, andit can be synthesized by a process described in, for example, JapanesePatent Laid-Open Publication No. 2010-285505 or Japanese PatentLaid-Open Publication No. 2011-197450.

(6) Fluorinated Aromatic Polymer-Based Resin

The fluorinated aromatic polymer-based resin is not specificallyrestricted provided that it is a polymer containing an aromatic ringhaving at least one fluorine and a repeating unit containing at leastone linkage selected from the group consisting of an ether linkage, aketone linkage, a sulfone linkage, am amide linkage, an imide linkageand an ester linkage, and it can be synthesized by a process describedin, for example, Japanese Patent Laid-Open Publication No. 2008-181121.

(7) Commercial Products

As commercial products of the transparent resins employable in thepresent invention, the following commercial products, etc. can bementioned. Examples of commercial products of the cyclic olefin-basedresins include Arton available from JSR Corporation, ZEONOR availablefrom Zeon Corporation, APEL available from Mitsui Chemicals, Inc. andTOPAS available from Polyplastics Co., Ltd. Examples of commercialproducts of the polyether sulfone-based resins include Sumika Excel PESavailable from Sumitomo Chemical Co., Ltd. Examples of commercialproducts of the polyimide-based resins include Neoprim L available fromMitsubishi Gas Chemical Company Inc. Examples of commercial products ofthe polycarbonate-based resins include PURE-ACE available from TeijinLtd. Examples of commercial products of the fluorene polycarbonate-basedresins include Yupizeta EP-5000 available from Mitsubishi Gas ChemicalCompany Inc. Examples of commercial products of the fluorenepolyester-based resins include OKP4HT available from Osaka Gas ChemicalsCo., Ltd. Examples of commercial products of the acrylic resins includeACRIVIEWA available from Nippon Shokubai Co., Ltd. Examples ofcommercial products of the silsesquioxane-based UV curing resins includeSilplus available from Shin-Nittetsu Chemical Co., Ltd.

<Near-Ultraviolet Absorbing Agent>

The near-ultraviolet absorbing agent employable in the present inventionis preferably at least one compound selected from the group consistingof an azomethine-based compound, an indole-based compound, abenzotriazole-based compound and a triazine-based compound, andpreferably has at least one absorption maximum in the wavelength regionof 300 to 420 nm. By adding such a near-ultraviolet absorbing agent inaddition to the near-infrared absorbing dye, an optical filter havingsmall incident angle dependence even in the near-ultraviolet wavelengthregion can be obtained.

(1) Azomethine-Based Compound

Although the azomethine-based compound is not specifically restricted,it can be represented by, for example, the following formula (5).

In the formula (5), R^(a1) to R^(a5) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, a carboxyl group, an alkyl groupof 1 to 15 carbon atoms, an alkoxy group of 1 to 9 carbon atoms or analkoxycarbonyl group of 1 to 9 carbon atoms.

(2) Indole-Based Compound

Although the Indole-based compound is not specifically restricted, itcan be represented by, for example, the following formula (6).

In the formula (6), R^(b1) to R^(b5) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, a carboxyl group, a cyano group,a phenyl group, an aralkyl group, an alkyl group of 1 to 9 carbon atoms,an alkoxy group of 1 to 9 carbon atoms or an alkoxycarbonyl group of 1to 9 carbon atoms.

(3) Benzotriazole-Based Compound

Although the benzotriazole-based compound is not specificallyrestricted, it can be represented by, for example, the following formula(7).

In the formula (7), R^(c1) to R^(c3) are each independently a hydrogenatom, a halogen atom, a hydroxyl group, an aralkyl group, an alkyl groupof 1 to 9 carbon atoms, an alkoxy group of 1 to 9 carbon atoms or analkyl group of 1 to 9 carbon atoms having an alkoxycarbonyl group of 1to 9 carbon atoms as an substituent.

(4) Triazine-Based Compound

Although the triazine-based compound is not specifically restricted, itcan be represented by, for example, the following formula (8), (9) or(10).

In the formulas (8) to (10), each R^(d1) is a hydrogen atom, an alkylgroup of 1 to 15 carbon atoms, a cycloalkyl group of 3 to 8 carbonatoms, an alkenyl group of 3 to 8 carbon atoms, an aryl group of 6 to 18carbon atoms, an alkylaryl group of 7 to 18 carbon atoms or an arylalkylgroup. These alkyl group, cycloalkyl group, alkenyl group, aryl group,alkylaryl group and arylalkyl group may be substituted by a hydroxylgroup, a halogen atom, an alkyl group of 1 to 12 carbon atoms or analkoxy group, and may be interrupted by an oxygen atom, a sulfur atom, acarbonyl group, an ester group, an amide group or an imino group. Thesubstitution and the interruption may be combined. R^(d2) to R^(d9) areeach independently a hydrogen atom, a halogen atom, a hydroxyl group, analkyl group of 1 to 15 carbon atoms, a cycloalkyl group of 3 to 8 carbonatoms, an alkenyl group of 3 to 8 carbon atoms, an aryl group of 6 to 18carbon atoms, an alkylaryl group of 7 to 18 carbon atoms or an arylalkylgroup.

<Other Components>

The resin substrate may further contain additives, such as antioxidant,ultraviolet absorbing agent, dye which absorbs near-infrared rays,fluorescence quencher and metal complex-based compound, within limitsnot detrimental to the effect of the present invention. When the resinsubstrate is produced by the later-described cast molding, production ofthe resin substrate can be facilitated by adding a leveling agent and ananti-foaming agent. These other components may be used singly or incombination of two or more kinds.

Examples of the antioxidants include 2,6-di-t-butyl-4-methylphenol,2,2′-dioxy-3,3′-di-t-butyl-5,5′-dimethyldiphenylmethane andtetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane.

Examples of the dyes which absorb near-infrared rays include adithiol-based dye, a diimonium-based dye, a porphyrin-based dye and acroconium-based dye. The structures of these dyes are not specificallyrestricted, and generally known dyes can be used provided that they donot impair the effect of the present invention.

These additives may be mixed together with a resin, etc. in theproduction of the resin substrate, or they may be added when a resin isproduced. Although the amount of such an additive is properly selectedaccording to the desired properties, it is usually 0.01 to 5.0 parts byweight, preferably 0.05 to 2.0 parts by weight, based on 100 parts byweight of the resin.

<Production Process for Resin Substrate>

The resin substrate can be formed by, for example, melt molding or castmolding, and if necessary, after molding, coating of the molded productwith coating agents, such as an antireflection agent, a hard coatingagent and/or an antistatic agent, can be carried out to produce theresin substrate.

(1) Melt Molding

The resin substrate can be produced by a process comprising melt-moldingpellets obtained by melt-kneading a resin and a near-infrared absorbingdye; a process comprising melt-molding a resin composition containing aresin and a near-infrared absorbing dye; a process comprisingmelt-molding pellets obtained by removing a solvent from a resincomposition containing a near-infrared absorbing dye, a resin and asolvent; or the like. Examples of the melt molding processes includeinjection molding, melt extrusion molding and blow molding.

(2) Cast Molding

The resin substrate can be also produced by a process comprising castinga resin composition containing a near-infrared absorbing dye, a resinand a solvent onto an appropriate base and removing the solvent; aprocess comprising casting a resin composition containing coatingagents, such as an antireflection agent, a hard coating agent and/or anantistatic agent, a near-infrared absorbing dye and a resin onto anappropriate base; a process comprising casting a curable compositioncontaining coating agents, such as an antireflection agent, a hardcoating agent and/or an antistatic agent, a near-infrared absorbing dyeand a resin onto an appropriate base, curing the composition and dryingthe cured product; or the like.

Examples of the bases include a glass plate, a steel belt, a steel drumand a transparent resin (e.g., polyester film, cyclic olefin-based resinfilm).

The resin substrate can be obtained by peeling the coating film from thebase, or as far as the effect of the present invention is not impaired,a laminate of the base and the coating film may be used as the resinsubstrate without peeling the base.

Further, the resin substrate can be also formed directly on an opticalpart by a process comprising coating an optical part made of a glassplate, quartz, transparent plastic or the like with the aforesaid resincomposition and drying the solvent, a process comprising coating theoptical part with the aforesaid curable composition, curing thecomposition and drying the cured product, or the like.

The amount of the residual solvent in the resin substrate obtained bythe above process is preferably as small as possible. Specifically, theamount of the residual solvent is preferably not more than 3% by weight,more preferably not more than 1% by weight, still more preferably notmore than 0.5% by weight, based on the weight of the resin substrate.When the amount of the residual solvent is in the above range, a resinsubstrate which is rarely deformed or rarely changed in properties andcan easily exert a desired function is obtained.

[Near-Infrared Reflecting Film]

The near-infrared reflecting film employable in the present invention isa film having an ability to reflect near-infrared rays. Examples of suchnear-infrared reflecting films include an aluminum deposited film, aprecious metal thin film, a resin film in which metal oxide fineparticles containing indium oxide as a main component and containing asmall amount of tin oxide are dispersed, and a dielectric multilayerfilm in which a high-refractive index material layer and alow-refractive index material layer are alternately laminated.

In the present invention, the near-infrared reflecting film may beprovided on one surface of the resin substrate, or may be provided onboth surfaces thereof. When it is provided on one surface, productioncost and ease of production are excellent, and when it is provided onboth surfaces, an optical filter having high strength and rarelysuffering warpage can be obtained.

Of the above near-infrared reflecting films, the dielectric multilayerfilm in which a high-refractive index material layer and alow-refractive index material layer are alternately laminated is morepreferable.

As the material to form the high-refractive index material layer, amaterial having a refractive index of not less than 1.7 can be used, anda material usually having a refractive index in the range of 1.7 to 2.5is selected. Such a material is, for example, a material containingtitanium oxide, zirconium oxide, tantalum pentaoxide, niobiumpentaoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide orindium oxide as a main component and containing titanium oxide, tinoxide and/or cerium oxide in a small amount (e.g., 0 to 10% based on themain component).

As the material to form the low-refractive index material layer, amaterial having a refractive index of not more than 1.6 can be used, anda material usually having a refractive index in the range of 1.2 to 1.6is selected. Examples of such materials include silica, alumina,lanthanum fluoride, magnesium fluoride and aluminum sodium hexafluoride.

The method for laminating the high-refractive index material layer andthe low-refractive index material layer is not specifically restrictedas far as a dielectric multilayer film wherein these layers arelaminated is formed. For example, the dielectric multilayer film can beformed by alternately laminating the high-refractive index materiallayer and the low-refractive index material layer directly on theaforesaid resin substrate through CVD method, sputtering, vacuumdeposition, ion-assisted deposition, ion plating or the like.

When the near-infrared wavelength to be cut is taken as λ (nm), thethickness of each of the high-refractive index material layer and thelow-refractive index material layer is preferably 0.1λ to 0.5λ. When thethickness is in this range, the optical film thickness calculated as aproduct (n×d) of the refractive index (n) and the film thickness (d),which is λ/4, and the thickness of each of the high-refractive indexmaterial layer and the low-refractive index material layer become almostthe same as each other, and from the relationship between the opticalproperties of reflection and refraction, cutting/transmission of aspecific wavelength tends to be able to be easily controlled.

The total number of laminated layers of the high-refractive indexmaterial layers and the low-refractive index material layers in thedielectric multilayer film is desired to be 5 to 60, preferably 10 to50.

In the case where warpage takes place in the substrate when thedielectric multilayer film is formed, a method of forming the dielectricmultilayer film on both surfaces of the substrate, a method ofirradiating the substrate surface where the dielectric multilayer filmhas been formed with electromagnetic waves such as ultraviolet rays, orthe like can be adopted in order to cope with the warpage. When thesubstrate surface is irradiated with the electromagnetic waves, theirradiation may be carried out during formation of the dielectricmultilayer film or may be carried out after the formation.

[Other Functional Films]

For the purpose of enhancing surface hardness of the resin substrate orthe near-infrared reflecting film, enhancing chemical resistance,preventing static electrification, removing flaws, etc., functionalfilms, such as an antireflection film, a hard coating film and anantistatic film, can be properly provided between the resin substrateand the near-infrared reflecting film such as a dielectric multilayerfilm or on a surface of the resin substrate opposite to the surfacewhere the near-infrared reflecting film has been provided or on asurface of the near-infrared reflecting film opposite to the surfacewhere the resin substrate has been provided.

The optical filter of the present invention may include one layercomposed of the above functional film or may include two or more layerseach of which is composed of the functional film. When the opticalfilter of the present invention includes two or more layers each ofwhich is composed of the functional film, it may include two or morelayers which are the same as one another or may include two or morelayers which are different from one another.

Although the method for laminating the functional film is notspecifically restricted, there can be mentioned a method of melt moldingor cast molding coating agents, such as an antireflection agent, a hardcoating agent and/or an antistatic agent, on the resin substrate or thenear-infrared reflecting film in the same manner as previouslydescribed.

The functional film can be produced also by applying a curablecomposition containing the coating agent, etc. onto the resin substrateor the infrared reflecting film using a bar coater or the like and thencuring the composition through ultraviolet light irradiation or thelike.

As the coating agent, an ultraviolet (UV)/electron beam (EB) curableresin, a thermosetting resin or the like can be mentioned, and specificexamples thereof include vinyl compounds, and urethane-based, urethaneacrylate-based, acrylate-based, epoxy-based and epoxy acrylate-basedresins. Examples of the curable compositions containing these coatingagents include vinyl-based, urethane-based, urethane acrylate-based,acrylate-based, epoxy-based and epoxy acrylate-based curablecompositions.

The curable composition may contain a polymerization initiator. As thepolymerization initiator, a publicly known photopolymerization initiatoror thermal polymerization initiator can be used, and aphotopolymerization initiator and a thermal polymerization initiator maybe used in combination. Such polymerization initiators may be usedsingly, or may be used in combination of two or more kind.

When the total amount of the curable composition is 100% by weight, theblending ratio of the polymerization initiator in the curablecomposition is preferably 0.1 to 10% by weight, more preferably 0.5 to10% by weight, still more preferably 1 to 5% by weight. When theblending ratio of the polymerization initiator is in the above range,the curable composition is excellent in curing property and handlingproperty, and a functional film having a desired hardness, such as anantireflection film, a hard coating film or an antistatic film, can beobtained.

To the curable composition, an organic solvent may be further added as asolvent, and as the organic solvent, a publicly known solvent can beused. Specific examples of the organic solvents include alcohols, suchas methanol, ethanol, isopropanol, butanol and octanol; ketones, such asacetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone;esters, such as ethyl acetate, butyl acetate, ethyl lactate,γ-butyrolactone, propylene glycol monomethyl ether acetate and propyleneglycol monoethyl ether acetate; ethers, such as ethylene glycolmonomethyl ether and diethylene glycol monobutyl ether; aromatichydrocarbons, such as benzene, toluene and xylene; and amides, such asdimethylformamide, dimethylacetamide and N-methylpyrrolidone. Thesesolvents may be used singly, or may be used in combination of two ormore kinds.

The thickness of the functional film is preferably 0.1 μm to 20 μm, morepreferably 0.5 μm to 10 μm, particularly preferably 0.7 μm to 5 μm.

For the purpose of enhancing adhesion between the resin substrate andthe functional film and/or the near-infrared reflecting film or adhesionbetween the functional film and the near-infrared reflecting film, thesurface of the resin substrate or the functional film may be subjectedto surface treatment, such as corona treatment or plasma treatment.

[Characteristics, Etc. of Optical Filter]

The optical filter of the present invention has the resin substrate. Onthis account, the optical filter of the present invention is excellentin transmittance property and is not limited when used. Further, sincethe squarylium-based compound and the cyanine-based compound containedin the resin substrate each have an absorption maximum in the wavelengthregion of 600 to 800 nm, they can absorb near-infrared lightefficiently, and by virtue of combination with the near-infraredreflecting film, an optical filter having small incident angledependence can be obtained.

In the optical filter of the present invention, the squarylium-basedcompound and the cyanine-based compound are used, and thereby, favorableabsorption property and visible light transmittance are compatible witheach other, the incident angle dependence can be reduced, and thescattered light intensity can be lowered. It is known that thesquarylium-based compound generally emits fluorescence during lightabsorption, and by using it in combination with the cyanine-basedcompound, reabsorption of fluorescence becomes possible, and as aresult, the scattered light intensity observed can be lowered. When thequantity of the transmitted light of the baseline in the spectrometry is100%, the scattered light intensity observed in the measurement using anoptical filter sample is preferably not more than 0.50%, particularlypreferably not more than 0.35%. When the scattered light intensity is inthis range, a favorable camera image free from a blur of image can beobtained.

[Uses of Optical Filter]

The optical filter of the present invention has a wide viewing angle andhas excellent near-infrared cutting ability, etc. Therefore, the opticalfilter is useful for correction of visibility of a sold-state imagesensor, such as CCD or CMOS image sensor of camera module. Inparticular, it is useful for digital still camera, camera for cellularphone, digital video camera, PC camera, surveillance camera, camera forautomobile, TV, car navigation system, personal digital assistant,personal computer, video game, handheld game console, fingerprintauthentication system, digital music player, etc. Moreover, the opticalfilter is useful also as a heat ray cut filter mounted on glass ofautomobile, building or the like.

<Solid-State Image Pickup Device>

The solid-state image pickup device of the present invention is equippedwith the optical filter of the present invention. Here, the solid-stateimage pickup device is an image sensor having a solid-state imagesensor, such as CCD or CMOS image sensor, and is specifically used fordigital still camera, camera for cellular phone, digital video camera,etc.

<Camera Module>

The camera module of the present invention is equipped with the opticalfilter of the present invention. Here, use of the optical filter of thepresent invention for a camera module is specifically described. InFIGS. 1A and 1B, sectional schematic views of camera modules are shown.

FIG. 1A is a sectional schematic view of a structure of a conventionalcamera module, and FIG. 1B is a sectional schematic view showing onestructure of a camera module, said structure being able to taken in thecase where the optical filter 6′ of the present invention is used. InFIG. 1B, the optical filter 6′ of the present invention is used above alens 5. However, the optical filter 6′ of the present invention can bealso used between a lens 5 and a sensor 7, as shown in FIG. 1A.

In the conventional camera module, light 10 needs to be incidentapproximately perpendicularly to the optical filter 6. On that account,the filter 6 needs to be arranged between the lens 5 and the sensor 7.

Since the sensor 7 is highly sensitive, there is a fear that it does notwork correctly even by the contact of dust or dirt of about 5 μm.Therefore, the filter 6 used above the sensor 7 needs to be a filterwhich is free from dust or dirt and contains no foreign matters.Further, from the viewpoints of characteristics of the sensor 7, it isnecessary to provide a given space between the filter 6 and the sensor7, and this has contributed to hindrance to lowering of height of thecamera module.

On the other hand, in the case of the optical filter 6′ of the presentinvention, there is no large difference in transmission wavelengthbetween the light that is incident perpendicularly to the filter 6′ andthe light that is incident at an angle of 30° to the perpendiculardirection to the filter 6′ (that is, the dependence of the absorption(transmission) wavelength on the incident angle is small). Therefore,there is no need to arrange the filter 6′ between the lens 5 and thesensor 7, and the filter 6′ can be arranged above the lens.

On this account, when the optical filter 6′ of the present invention isused for a camera module, handling of the cameral module is facilitated,and there is no need to provide a given space between the filter 6′ andthe sensor 7, so that lowering of height of the camera module becomespossible.

EXAMPLES

The present invention is more specifically described with reference tothe following examples, but it should be construed that the presentinvention is in no way limited to those examples. The term “part (s)”means “part (s) by weight” unless otherwise noted. Methods for measuringproperty values and methods for evaluating properties are as follows.

<Molecular Weight>

Taking into consideration the solubility of each resin in a solvent,etc., a molecular weight of the resin was measured by the followingmethod (a) or (b).

-   -   (a) Using a gel permeation chromatography (GPC) apparatus (150C        type, column: H type column available from Tosoh Corporation,        developing solvent: o-dichlorobenzene) manufactured by WATERS        Corporation, a weight-average molecular weight (Mw) and a        number-average molecular weight (Mn) in terms of standard        polystyrene were measured.

(b) Using a GPC apparatus (HLC-8220 type, column: TSKgel α-M, developingsolvent: THF) manufactured by Tosoh Corporation, a weight-averagemolecular weight (Mw) and a number-average molecular weight (Mn) interms of standard polystyrene were measured.

With regard to the resin synthesized in the later-described ResinSynthesis Example 3, measurement of a molecular weight by the abovemethod was not carried out, but measurement of an inherent viscosity bythe following method (c) was carried out.

(c) A part of a polyimide resin solution was introduced into anhydrousmethanol to precipitate a polyimide resin, and filtration was carriedout to separate the resin from an unreacted monomer. Then, 0.1 g ofpolyimide obtained by vacuum drying the resulting resin at 80° C. for 12hours was dissolved in 20 mL of N-methyl-2-pyrrolidone, and an inherentviscosity (μ) at 30° C. was determined using a Cannon-Fenske viscometerand the following formula.μ={ln(t _(s) /t ₀)}/C

t₀: flow time of solvent

t_(s): flow time of dilute polymer solution

C: 0.5 g/dL

<Glass Transition Temperature (Tg)>

Using a differential scanning calorimeter (DSC 6200) manufactured by SIINanotechnology Inc., a glass transition temperature was measured at aheating rate of 20° C./min in a stream of nitrogen.

<Spectral Transmittance>

Using a spectrophotometer (U-4100) manufactured by Hitachi High-TechScience Corporation, an absorption maximum, a transmittance in eachwavelength region, (Xa) and (Xb) were measured.

Here, with regard to the transmittance measured in the perpendiculardirection to the optical filter, a transmittance of light transmittedperpendicularly to the filter was measured, as shown in FIG. 2. Withregard to the transmittance measured at an angle of 30° to theperpendicular direction to the optical filter, a transmittance of lighttransmitted at an angle of 30° to the perpendicular direction to thefilter was measured, as shown in FIG. 3.

This transmittance was a transmittance measured by the use of thespectrophotometer under such conditions that the light is incidentperpendicularly to the substrate and the filter, except the case ofmeasurement of (Xb). In the case of measurement of (Xb), thetransmittance was a transmittance measured by the use of thespectrophotometer under such conditions that the light is incident at anangle of 30° to the perpendicular direction to the filter.

<Scattered Light Intensity>

Using a spectrophotometer (U-4100) manufactured by Hitachi High-TechScience Corporation, a mean intensity of scattered light in thewavelength region of 700 nm to 715 nm was measured.

In the measurement of a scattered light intensity, a part of anintegrating sphere of the spectrophotometer was replaced with a carbonfeather sheet of black color exhibiting little light reflection so thatthe light beam having entered the integrating sphere should not bereflected or scattered inside the integrating sphere, as shown in FIG.4. By adopting such a measuring method, the intensity of light scatteredon the optical filter portion can be measured. In the scattered lightthat is measurable herein, not only the light physically scattered onthe optical filter portion but also fluorescence emitted by thesquarylium-based compound during light absorption is contained.

Synthesis Examples

Squarylium-based compounds, phthalocyanine-based compounds,cyanine-based compounds, near-ultraviolet absorbing agents and otherdyes used in the following examples can be synthesized by methodsgenerally known, and for example, they can be synthesized referring tothe methods described in Japanese Patent No. 3366697, Japanese PatentNo. 2846091, Japanese Patent No. 2864475, Japanese Patent No. 3703869,Japanese Patent Laid-Open Publication No. 1985-228448, Japanese PatentLaid-Open Publication No. 1989-146846, Japanese Patent Laid-OpenPublication No. 1989-228960, Japanese Patent No. 4081149, JapanesePatent Laid-Open Publication No. 1988-124054, “Phthalocyanine—Chemistryand Functions—” (IPC, 1997), Japanese Patent Laid-Open Publication No.2007-169315, Japanese Patent Laid-Open Publication No. 2009-108267,Japanese Patent Laid-Open Publication No. 2010-241873, Japanese PatentNo. 3699464, Japanese Patent No. 4740631, etc.

Resin Synthesis Example 1

In a reaction container purged with nitrogen, 100 parts of8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodec-3-ene(also referred to as “DNM” hereinafter) represented by the followingformula (a), 18 parts of 1-hexene (molecular weight modifier) and 300parts of toluene (solvent for ring-opening polymerization reaction) wereplaced, and this solution was heated to 80° C. Then, to the solution inthe reaction container, 0.2 part of a toluene solution oftriethylaluminum (0.6 mol/liter) and 0.9 part of a toluene solution ofmethanol-modified tungsten hexachloride (concentration: 0.025 mol/liter)were added as polymerization catalysts, and the resulting solution washeated and stirred at 80° C. for 3 hours to perform ring-openingpolymerization reaction, whereby a ring-opened polymer solution wasobtained. The polymerization conversion ratio in this polymerizationreaction was 97%.

In an autoclave, 1,000 parts of the ring-opened polymer solutionobtained as above were placed, and to this ring-opened polymer solution,0.12 part of RuHCl(CO) [P(C₆H₅)₃]₃ was added, and they were heated andstirred for 3 hours under the conditions of a hydrogen gas pressure of100 kg/cm² and a reaction temperature of 165° C. to performhydrogenation reaction.

After the resulting reaction solution (hydrogenated polymer solution)was cooled, the hydrogen gas pressure was released. This reactionsolution was poured into a large amount of methanol, and the resultingprecipitate was separated and recovered. Then, the precipitate was driedto obtain a hydrogenated polymer (also referred to as a “resin A”hereinafter). The resulting resin A had a number-average molecularweight (Mn) of 32,000, a weight-average molecular weight (Mw) of 137,000and a glass transition temperature (Tg) of 165° C.

Resin Synthesis Example 2

In a 3-liter four-neck flask, 35.12 g (0.253 mol) of2,6-difluorobenzonitrile, 87.60 g (0.250 mol) of 9,9-bis(4-hydroxyphenyl) fluorene, 41.46 g (0.300 mol) of potassium carbonate,443 g of N,N-dimethylacetamide (also referred to as “DMAc” hereinafter)and 111 g of toluene were placed. Subsequently, to the four-neck flask,a thermometer, a stirrer, a three-way cock with a nitrogen feed pipe, aDean-Stark tube and a cooling pipe were fixed.

Then, the flask was purged with nitrogen. Thereafter, the resultingsolution was subjected to reaction at 140° C. for 3 hours, and waterproduced was removed from the Dean-Stark tube whenever necessary. Whenproduction of water came to be not detected, the temperature was slowlyraised up to 160° C., and the reaction was carried out at the sametemperature for 6 hours.

After the reaction solution was cooled down to room temperature (25°C.), a salt produced was removed by a filter paper, then the filtratewas introduced into methanol to perform reprecipitation, and filtrationwas carried out to isolate a filter residue (residue). The resultingfilter residue was vacuum dried at 60° C. for one night to obtain awhite powder (also referred to as a “resin B” hereinafter) (yield: 95%).The resulting resin B had a number-average molecular weight (Mn) of75,000, a weight-average molecular weight (Mw) of 188,000 and a glasstransition temperature (Tg) of 285° C.

Resin Synthesis Example 3

In a 500-mL five-neck flask equipped with a thermometer, a stirrer, anitrogen feed pipe, a dropping funnel with a side tube, a Dean-Starktube and a cooling pipe, 27.66 g (0.08 mol) of1,4-bis(4-amino-α,α-dimethylbenzyl)benzene and 7.38 g (0.02 mol) of4,4′-bis (4-aminophenoxy) biphenyl were placed in a stream of nitrogen,and they were dissolved in 68.65 g of γ-butyrolactone and 17.16 g ofN,N-dimethylacetamide. The resulting solution was cooled to 5° C. usingan ice water bath, and with maintaining the solution at the sametemperature, 22.62 g (0.1 mol) of 1,2,4,5-cyclohexanetetracarboxylicdianhydride and 0.50 g (0.005 mol) of triethylamine as an imdizationcatalyst were added all together. After the addition was completed, thetemperature was raised to 180° C., and with removing the distillatewhenever necessary, the reaction solution was refluxed for 6 hours.After the reaction was completed, air cooling was carried out until theinternal temperature became 100° C. Thereafter, 143.6 g ofN,N-dimethylacetamide was added to dilute the reaction solution, andwith stirring, the resulting solution was cooled to obtain 264.16 g of apolyimide resin solution having a solid concentration of 20% by weight.A part of the polyimide resin solution was poured into 1 liter ofmethanol to precipitate polyimide. The polyimide was filtered off,washed with methanol and then dried for 24 hours in a vacuum dryer at100° C. to obtain a white powder (also referred to as a “resin C”hereinafter). When an IR spectrum of the resulting resin C was measured,absorption at 1704 cm⁻¹ and 1770 cm⁻¹ characteristic of an imide groupwas observed. The resin C had a glass transition temperature (Tg) of310° C., and the inherent viscosity measurement resulted in 0.87.

Resin Synthesis Example 4

In a 50-liter reactor equipped with a stirrer and a distillation device,9.167 kg (20.90 mol) of 9,9-bis (4-(2-hydroxyethoxy)phenyl)fluorene,4.585 kg (20.084 mol) of bisphenol A, 9.000 kg (42.01 mol) of diphenylcarbonate and 0.02066 kg (2.459×10⁻⁴ mol) of sodium hydrogencarbonatewere placed, and they were heated and stirred at 215° C. over a periodof 1 hour at 760 Torr in a nitrogen atmosphere. Thereafter, the degreeof vacuum was adjusted to 150 Torr over a period of 15 minutes, and thesystem was maintained for 20 minutes under the conditions of 215° C. and150 Torr to perform transesterification reaction. Further, thetemperature was raised up to 240° C. at a rate of 37.5° C./hr, and thesystem was maintained at 240° C. and 150 Torr for 10 minutes.Thereafter, the system was adjusted to 100 Torr over a period of 10minutes, and was maintained at 240° C. and 120 Torr for 70 minutes.Thereafter, the system was adjusted to 100 Torr over a period of 10minutes, and was maintained at 240° C. and 100 Torr for 10 minutes.Further, the system was adjusted to not more than 1 Torr over a periodof 40 minutes, and stirring was carried out for 10 minutes under theconditions of 240° C. and 1 Torr to perform polymerization reaction.After the reaction was completed, nitrogen was fed to the reactor topressurize the reactor, and with pelletizing the resulting polycarbonateresin (also referred to as a “resin D” hereinafter), the pellets weretaken out. The resulting resin D had a weight-average molecular weightof 41,000 and a glass transition temperature (Tg) of 152° C.

Resin Synthesis Example 5

In a reactor, 0.8 mol of9,9-bis{4-(2-hydroxyethoxy)-3,5-dimethylphenyl}fluorene, 2.2 mol ofethylene glycol and 1.0 mol of dimethyl isophthalate were placed, andwith stirring, they were slowly heated and melted to performtransestrification reaction. Thereafter, 20×10⁻⁴ mol of germanium oxidewas added, and with slowly carrying out elevation of temperature andreduction of pressure until a temperature of 290° C. and a pressure ofnot more than 1 Torr were reached, ethylene glycol was removed.Thereafter, the contents were taken out of the reactor to obtain pelletsof a polyester resin (also referred to as a “resin E” hereinafter). Theresulting resin E had a number-average molecular weight of 40,000 and aglass transition temperature of 145° C.

Resin Synthesis Example 6

In a reactor equipped with a thermometer, a cooling pipe, a gas feedpipe and a stirrer, 16.74 parts of 4,4′-bis(2,3,4,5,6-pentafluorobenzoyl)diphenyl ether (BPDE), 10.5 parts of9,9-bis (4-hydroxyphenyl) fluorene (HF), 4.34 parts of potassiumcarbonate and 90 parts of DMAc were placed. This mixture was heated to80° C. and subjected to reaction for 8 hours. After the reaction wascompleted, the reaction solution was added to a 1% acetic acid aqueoussolution with vigorously stirring by a blender. The reaction productprecipitated was filtered off, washed with distilled water and methanoland then vacuum dried to obtain fluorinated polyether ketone (alsoreferred to as a “resin F” hereinafter). The resulting resin F had anumber-average molecular weight of 71,000 and a glass transitiontemperature (Tg) of 242° C.

Example A1

In a container, 100 parts by weight of the resin A obtained in SynthesisExample 1, 0.03 part by weight of a squarylium-based compound (a-16),0.01 part by weight of a phthalocyanine-based compound (b-11) andmethylene chloride were placed to obtain a solution (ex1) having a resinconcentration of 20% by weight. Then, the resulting solution was castonto a smooth glass plate and dried at 20° C. for 8 hours, andthereafter, the resulting coating film was peeled off from the glassplate. The coating film thus peeled off was further dried at 100° C. for8 hours under reduced pressure to obtain a substrate having a thicknessof 0.1 mm, a length of 60 mm and a width of 60 mm.

A spectral transmittance of this substrate was measured, and anabsorption maximum wavelength, a transmittance at the absorption maximumwavelength and a transmittance in the visible wavelength region weredetermined. The results are set forth in Table 10 and Table 11.

Subsequently, on one surface of the resulting substrate, a multilayerdeposited film [silica (SiO₂, thickness: 83 to 199 nm) layer and titania(TiO₂, thickness: 101 to 125 nm) layer were alternately laminated,number of layers laminated: 20], which reflected near-infrared rays at adeposition temperature of 100° C., was formed, and on the other surfaceof the substrate, a multilayer deposited film [silica (SiO₂, thickness:77 to 189 nm) layer and titania (TiO₂, thickness: 84 to 118 nm) layerwere alternately laminated, number of layers laminated: 26], whichreflected near-infrared rays at a deposition temperature of 100° C., wasformed, whereby an optical filter having a thickness of 0.105 mm wasobtained. A spectral transmittance of this optical filter was measured,and optical properties in each wavelength region were evaluated. Theresults are set forth in Table 10.

The mean transmittance in the wavelength region of 430 to 580 nm was91%, and the mean transmittance in the wavelength region of 800 to 1000nm was 1% or less.

Example A2

On one surface of the substrate having a thickness of 0.1 mm, a lengthof 60 mm and a width of 60 mm, which had been obtained in Example A1, amultilayer deposited film [silica (SiO₂, thickness: 120 to 190 nm) layerand titania (TiO₂, thickness: 70 to 120 nm) layer were alternatelylaminated, number of layers laminated: 40], which reflectednear-infrared rays at a deposition temperature of 100° C., was formed toproduce an optical filter having a thickness of 0.104 mm, and theoptical filter was evaluated. The results are set forth in Table 10.

[Example A3] to [Example A23] and [Comparative Example A1] to[Comparative Example A6]

Optical filters each having a thickness of 0.105 mm were produced in thesame manner as in Example A1, except that the resins, the solvents, thedyes and the film drying conditions shown in Table 9 were adopted. Theconditions for producing optical filters are set forth in Table 9, andthe evaluation results are set forth in Table 10 and Table 11. In Table9, the amount of each resin added is 100 parts by weight, and theconcentration of each resin solution is 20% by weight. various compoundsother than the resins A to F, the squarylium-based compounds and thephthalocyanine-based compounds, and solvents used in the examples andthe comparative examples are as follows.

Resin G: cyclic olefin-based resin “ZEONOR 1420R” (available from ZeonCorporation)

Resin H: cyclic olefin-based resin “APEL #6015” (available from MitsuiChemicals, Inc.)

Resin I: polycarbonate-based resin “PURE-ACE” (available from TeijinLimited)

Resin J: polyether sulfone-based resin “SUMILITE FS-1300” (availablefrom Sumitomo Bakelite Co., Ltd.)

Resin K: heat-resistant acrylic resin “ACRIVIEWA” (available from NipponShokubai Co., Ltd.)

Solvent (1): methylene chloride

Solvent (2): N,N-dimethylacetamide

Solvent (3): ethyl acetate/toluene (ratio by weight: 5/5)

Solvent (4): cyclohexane/xylene (ratio by weight: 7/3)

Solvent (5): cyclohexane/methylene chloride (ratio by weight: 99/1)

Solvent (6): N-methyl-12-pyrrolidone

Compound (11): triazine-based compound represented by the followingformula (11)

Compound (12): indole-based compound represented by the followingformula (12)

Compound (13): nickel complex compound represented by the followingformula (13)

Compound (14): cyanine-based compound represented by the followingformula (14)

The film drying conditions in the examples and the comparative examplesin Table 9 are as follows.

Conditions (1): 20° C./8 hr→100° C./8 hr under reduced pressure

Conditions (2): 60° C./8 hr→80° C./8 hr→140° C./8 hr under reducedpressure

Conditions (3): 60° C./8 hr→80° C./8 hr→100° C./24 hr under reducedpressure

Conditions (4): 40° C./4 hr→60° C./4 hr→100° C./8 hr under reducedpressure

TABLE 9 Composition of resin solution Resin Solvent Squarylium-basedcompound Phthalocyanine-based compound Ex. A1 resin A solvent (1) (a-16)0.03 part by weight (b-11) 0.01 part by weight Ex. A2 resin A solvent(1) (a-16) 0.03 part by weight (b-11) 0.01 part by weight Ex. A3 resin Asolvent (1) (a-16) 0.03 part by weight (b-3) 0.01 part by weight Ex. A4resin A solvent (1) (a-16) 0.03 part by weight (b-20) 0.01 part byweight Ex. A5 resin A solvent (1) (a-22) 0.03 part by weight (b-4) 0.01part by weight Ex. A6 resin A solvent (1) (a-22) 0.03 part by weight(b-11) 0.01 part by weight Ex. A7 resin A solvent (1) (a-33) 0.03 partby weight (b-16) 0.02 part by weight Ex. A8 resin A solvent (1) (a-8)0.03 part by weight (b-47) 0.01 part by weight Ex. A9 resin A solvent(1) (a-16) 0.03 part by weight (b-11) 0.01 part by weight Ex. A10 resinA solvent (1) (a-16) 0.03 part by weight (b-11) 0.01 part by weight Ex.A11 resin B solvent (1) (a-16) 0.03 part by weight (b-11) 0.01 part byweight Ex. A12 resin B solvent (1) (a-16) 0.03 part by weight (b-3) 0.01part by weight Ex. A13 resin B solvent (1) (a-8) 0.03 part by weight(b-11) 0.02 part by weight Ex. A14 resin B solvent (1) (a-22) 0.03 partby weight (b-16) 0.01 part by weight Ex. A15 resin C solvent (2) (a-16)0.03 part by weight (b-11) 0.01 part by weight Ex. A16 resin D solvent(1) (a-16) 0.03 part by weight (b-11) 0.01 part by weight Ex. A17 resinE solvent (1) (a-16) 0.03 part by weight (b-11) 0.01 part by weight Ex.A18 resin F solvent (3) (a-16) 0.03 part by weight (b-11) 0.01 part byweight Ex. A19 resin G solvent (4) (a-16) 0.03 part by weight (b-11)0.01 part by weight Ex. A20 resin H solvent (5) (a-16) 0.03 part byweight (b-11) 0.01 part by weight Ex. A21 resin I solvent (1) (a-16)0.03 part by weight (b-11) 0.01 part by weight Ex. A22 resin J solvent(6) (a-16) 0.03 part by weight (b-11) 0.01 part by weight Ex. A23 resinK solvent (1) (a-16) 0.03 part by weight (b-11) 0.01 part by weightComp. resin A solvent (1) — — Ex. A1 Comp. resin A solvent (1) — — Ex.A2 Comp. resin A solvent (1) — — Ex. A3 Comp. resin A solvent (1) (a-16)0.04 part by weight — Ex. A4 Comp. resin A solvent (1) — (b-11) 0.04part by weight Ex. A5 Comp. resin A solvent (1) (a-16) 0.03 part byweight — Ex. A6 Composition of resin solution Film drying Othercompounds conditions Constitution of multilayer deposited film Ex. A1 —condition (1) both surfaces (20 layers + 26 layers) Ex. A2 — condition(1) one surface 40 layers Ex. A3 — condition (1) both surfaces (20layers + 26 layers) Ex. A4 — condition (1) both surfaces (20 layers + 26layers) Ex. A5 — condition (1) both surfaces (20 layers + 26 layers) Ex.A6 — condition (1) both surfaces (20 layers + 26 layers) Ex. A7 —condition (1) both surfaces (20 layers + 26 layers) Ex. A8 — condition(1) both surfaces (20 layers + 26 layers) Ex. A9 compound(11) condition(1) both surfaces (20 layers + 26 layers) 0.40 part by weight Ex. A10compound(11) condition (1) both surfaces (20 layers + 26 layers) 0.40part by weight compound(12) 0.10 part by weight Ex. A11 — condition (1)both surfaces (20 layers + 26 layers) Ex. A12 — condition (1) bothsurfaces (20 layers + 26 layers) Ex. A13 — condition (1) both surfaces(20 layers + 26 layers) Ex. A14 — condition (1) both surfaces (20layers + 26 layers) Ex. A15 — condition (2) both surfaces (20 layers +26 layers) Ex. A16 — condition (1) both surfaces (20 layers + 26 layers)Ex. A17 — condition (1) both surfaces (20 layers + 26 layers) Ex. A18 —condition (2) both surfaces (20 layers + 26 layers) Ex. A19 — condition(3) both surfaces (20 layers + 26 layers) Ex. A20 — condition (4) bothsurfaces (20 layers + 26 layers) Ex. A21 — condition (1) both surfaces(20 layers + 26 layers) Ex. A22 — condition (2) both surfaces (20layers + 26 layers) Ex. A23 — condition (1) both surfaces (20 layers +26 layers) Comp. — condition (1) both surfaces (20 layers + 26 layers)Ex. A1 Comp. compound(13) condition (1) both surfaces (20 layers + 26layers) Ex. A2 0.50 part by weight Comp. compound(14) condition (1) bothsurfaces (20 layers + 26 layers) Ex. A3 0.04 part by weight Comp. —condition (1) both surfaces (20 layers + 26 layers) Ex. A4 Comp. —condition (1) both surfaces (20 layers + 26 layers) Ex. A5 Comp.compound(13) condition (1) both surfaces (20 layers + 26 layers) Ex. A60.10 part by weight

TABLE 10 Transparent Optical filter resin substrate Mean value of Meanvalue of Scattered light Absorption transmittances in transmittances inintensity in maximum wavelength region of wavelength region ofwavelength region of wavelength 430 nm to 580 nm 800 nm to 1000 nm |Xa −Xb| 700 nm to 715 nm Ex. A1 698 nm 91% 1% or less 3 nm 0.21% Ex. A2 698nm 91% 1% or less 3 nm 0.21% Ex. A3 703 nm 90% 1% or less 3 nm 0.20% Ex.A4 700 nm 90% 1% or less 4 nm 0.20% Ex. A5 674 nm 89% 1% or less 4 nm0.20% Ex. A6 673 nm 89% 1% or less 4 nm 0.21% Ex. A7 676 nm 89% 1% orless 5 nm 0.23% Ex. A8 688 nm 90% 1% or less 4 nm 0.21% Ex. A9 360 nm,698 nm 91% 1% or less 3 nm 0.22% Ex. A10 364 nm, 698 nm 91% 1% or less 3nm 0.22% Ex. A11 706 nm 88% 1% or less 5 nm 0.22% Ex. A12 710 nm 87% 1%or less 4 nm 0.23% Ex. A13 699 nm 87% 1% or less 6 nm 0.24% Ex. A14 684nm 87% 1% or less 6 nm 0.23% Ex. A15 708 nm 87% 1% or less 5 nm 0.24%Ex. A16 705 nm 87% 1% or less 6 nm 0.23% Ex. A17 707 nm 88% 1% or less 5nm 0.24% Ex. A18 706 nm 87% 1% or less 6 nm 0.24% Ex. A19 697 nm 90% 1%or less 4 nm 0.22% Ex. A20 699 nm 89% 1% or less 4 nm 0.21% Ex. A21 706nm 87% 1% or less 5 nm 0.21% Ex. A22 712 nm 87% 1% or less 7 nm 0.24%Ex. A23 697 nm 91% 1% or less 5 nm 0.24% Comp. none 92% 1% or less 25nm  0.06% Ex. A1 Comp. 847 nm 86% 1% or less 24 nm  0.07% Ex. A2 Comp.998 nm 85% 1% or less 24 nm  0.06% Ex. A3 Comp. 698 nm 91% 1% or less 3nm 0.63% Ex. A4 Comp. 695 nm 91% 1% or less 18 nm  0.04% Ex. A5 Comp.700 nm, 847 nm 88% 1% or less 5 nm 0.61% Ex. A6

TABLE 11 Transparent resin substrate Absorption maximum wavelengthPhthalocyanine- Squarylium-based based Difference in absorption compoundcompound maximum wavelength Ex. A1 698 nm 700 nm 2 nm Ex. A2 698 nm 700nm 2 nm Ex. A3 698 nm 730 nm 32 nm  Ex. A4 698 nm 722 nm 24 nm  Ex. A5671 nm 702 nm 31 nm  Ex. A6 671 nm 700 nm 29 nm  Ex. A7 673 nm 690 nm 17nm  Ex. A8 686 nm 695 nm 9 nm Ex. A9 698 nm 700 nm 2 nm Ex. A10 698 nm700 nm 2 nm Ex. A11 705 nm 707 nm 2 nm Ex. A12 705 nm 739 nm 34 nm  Ex.A13 696 nm 707 nm 11 nm  Ex. A14 680 nm 694 nm 14 nm  Ex. A15 707 nm 710nm 3 nm Ex. A16 705 nm 707 nm 2 nm Ex. A17 706 nm 709 nm 3 nm Ex. A18706 nm 708 nm 2 nm Ex. A19 697 nm 699 nm 2 nm Ex. A20 698 nm 701 nm 3 nmEx. A21 705 nm 707 nm 2 nm Ex. A22 711 nm 713 nm 2 nm Ex. A23 697 nm 699nm 2 nm Comp. — — — Ex. A1 Comp. — — — Ex. A2 Comp. — — — Ex. A3 Comp.698 nm — — Ex. A4 Comp. — 700 nm — Ex. A5 Comp. 698 nm — — Ex. A6

Example B1

In a container, 100 parts by weight of the resin A obtained in SynthesisExample 1, 0.03 part by weight of a squarylium-based compound (a-16),0.01 part by weight of a cyanine-based compound (c-19) and methylenechloride were placed to obtain a solution (ex1) having a resinconcentration of 20% by weight. Then, the resulting solution was castonto a smooth glass plate and dried at 20° C. for 8 hours, andthereafter, the resulting coating film was peeled off from the glassplate. The coating film thus peeled off was further dried at 100° C. for8 hours under reduced pressure to obtain a substrate having a thicknessof 0.1 mm, a length of 60 mm and a width of 60 mm.

A spectral transmittance of this substrate was measured, and anabsorption maximum wavelength, a transmittance at the absorption maximumwavelength and a transmittance in the visible wavelength region weredetermined. The results are set forth in Table 13.

Subsequently, on one surface of the resulting substrate, a multilayerdeposited film [silica (SiO₂, thickness: 83 to 199 nm) layer and titania(TiO₂, thickness: 101 to 125 nm) layer were alternately laminated,number of layers laminated: 20], which reflected near-infrared rays at adeposition temperature of 100° C., was formed, and on the other surfaceof the substrate, a multilayer deposited film [silica (SiO₂, thickness:77 to 189 nm) layer and titania (TiO₂, thickness: 84 to 118 nm) layerwere alternately laminated, number of layers laminated: 26], whichreflected near-infrared rays at a deposition temperature of 100° C., wasformed, whereby an optical filter having a thickness of 0.105 mm wasobtained. A spectral transmittance of this optical filter was measured,and optical properties in each wavelength region were evaluated. Theresults are set forth in Table 13.

The mean transmittance in the wavelength region of 430 to 580 nm was90%, and the mean transmittance in the wavelength region of 800 to 1000nm was 1% or less.

Example B2

On one surface of the substrate having a thickness of 0.1 mm, a lengthof 60 mm and a width of 60 mm, which had been obtained in Example B1, amultilayer deposited film [silica (SiO₂, thickness: 120 to 190 nm) layerand titania (TiO₂, thickness: 70 to 120 nm) layer were alternatelylaminated, number of layers laminated: 40], which reflectednear-infrared rays at a deposition temperature of 100° C., was formed toproduce an optical filter having a thickness of 0.104 mm, and theoptical filter was evaluated. The results are set forth in Table 13.

[Example B3] to [Example B15] and [Comparative Example B1] to[Comparative Example B4]

Optical filters each having a thickness of 0.105 mm were produced in thesame manner as in Example B1, except that the resins, the solvents, thedyes and the film drying conditions shown in Table 12 were adopted. Theconditions for producing optical filters are set forth in Table 12, andthe evaluation results are set forth in Table 13. In Table 12, theamount of each resin added is 100 parts by weight, and the concentrationof each resin solution is 20% by weight. The resins G to K other thanthe resins A to F produced in the aforesaid synthesis examples, thesolvents and the film drying conditions in Table 12 are the same as theresins G to K, the solvents and the film drying conditions in Table 9.

TABLE 12 Composition of resin solution Constitution Squarylium-basedCyanine-based Other Film drying of multilayer Resin Solvent compoundcompound compounds conditions deposited film Ex. B1 resin A solvent (1)(a-16) 0.03 (c-19) 0.01 — condition (1) both surfaces part by weightpart by weight (20 layers + 26 layers) Ex. B2 resin A solvent (1) (a-16)0.03 (c-19) 0.01 — condition (1) one surface part by weight part byweight 40 layers Ex. B3 resin A solvent (1) (a-22) 0.02 (c-18) 0.02 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B4 resin A solvent (1) (a-22) 0.02 (c-19) 0.02 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B5 resin B solvent (1) (a-16) 0.03 (c-19) 0.01 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B6 resin C solvent (2) (a-22) 0.02 (c-18) 0.02 —condition (2) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B7 resin C solvent (2) (a-16) 0.03 (c-19) 0.01 —condition (2) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B8 resin D solvent (1) (a-16) 0.03 (c-19) 0.01 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B9 resin E solvent (1) (a-16) 0.03 (c-19) 0.01 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B10 resin F solvent (3) (a-16) 0.03 (c-19) 0.01 —condition (2) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B11 resin G solvent (4) (a-16) 0.03 (c-19) 0.01 —condition (3) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B12 resin H solvent (5) (a-16) 0.03 (c-19) 0.01 —condition (4) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B13 resin I solvent (1) (a-16) 0.03 (c-19) 0.01 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B14 resin J solvent (6) (a-16) 0.03 (c-19) 0.01 —condition (2) both surfaces part by weight part by weight (20 layers +26 layers) Ex. B15 resin K solvent (1) (a-16) 0.03 (c-19) 0.01 —condition (1) both surfaces part by weight part by weight (20 layers +26 layers) Comp. resin A solvent (1) — — — condition (1) both surfacesEx. B1 (20 layers + 26 layers) Comp. resin A solvent (1) (a-16) 0.04 — —condition (1) both surfaces Ex. B2 part by weight (20 layers + 26layers) Comp. resin A solvent (1) — (c-19) 0.04 — condition (1) bothsurfaces Ex. B3 part by weight (20 layers + 26 layers) Comp. resin Asolvent (1) (a-16) 0.02 (c-18) 0.02 — condition (1) both surfaces Ex. B4part by weight part by weight (20 layers + 26 layers)

TABLE 13 Optical filter Scattered Transparent resin substrate Mean valueof Mean value of light Absorption maximum wavelength transmittancestransmittances intensity Difference in in wavelength in wavelength inwavelength Squarylium- Cyanine- absorption region of region of region ofbased based maximum 430 nm to 800 nm to 700 nm to compound compoundwavelength 580 nm 1000 nm |Xa-Xb| 715 nm Ex. B1 698 nm 725 nm 27 nm 90%1% or less 3 nm 0.21% Ex. B2 698 nm 725 nm 27 nm 90% 1% or less 3 nm0.21% Ex. B3 671 nm 695 nm 24 nm 91% 1% or less 4 nm 0.24% Ex. B4 671 nm725 nm 54 nm 90% 1% or less 4 nm 0.24% Ex. B5 707 nm 733 nm 26 nm 76% 1%or less 5 nm 0.20% Ex. B6 677 nm 702 nm 25 nm 88% 1% or less 4 nm 0.23%Ex. B7 710 nm 737 nm 27 nm 86% 1% or less 5 nm 0.24% Ex. B8 705 nm 732nm 27 nm 86% 1% or less 6 nm 0.24% Ex. B9 708 nm 735 nm 27 nm 87% 1% orless 5 nm 0.23% Ex. B10 709 nm 736 nm 27 nm 86% 1% or less 6 nm 0.24%Ex. B11 697 nm 724 nm 27 nm 89% 1% or less 4 nm 0.22% Ex. B12 698 nm 725nm 27 nm 88% 1% or less 4 nm 0.21% Ex. B13 707 nm 734 nm 27 nm 86% 1% orless 5 nm 0.21% Ex. B14 712 nm 739 nm 27 nm 86% 1% or less 7 nm 0.24%Ex. B15 697 nm 724 nm 27 nm 90% 1% or less 5 nm 0.24% Comp. — — — 92% 1%or less 25 nm  0.06% Ex. B1 Comp. 698 nm — — 91% 1% or less 3 nm 0.63%Ex. B2 Comp. — 725 nm — 90% 1% or less 25 nm  0.04% Ex. B3 Comp. 698 nm695 nm −3 nm 90% 1% or less 3 nm 0.42% Ex. B4

INDUSTRIAL APPLICABILITY

The optical filter of the present invention can be favorably used fordigital still camera, camera for cellular phone, digital video camera,PC camera, surveillance camera, camera for automobile, TV, carnavigation system, personal digital assistant, personal computer, videogame, handheld game console, fingerprint authentication system, digitalmusic player, etc. Moreover, the optical filter can be favorably usedalso as a heat ray cut filter mounted on glass or the like ofautomobile, building, etc.

REFERENCE SIGNS LIST

-   -   1: camera module    -   2: lens barrel    -   3: flexible substrate    -   4: hollow package    -   5: lens    -   6: optical filter    -   6′: optical filter of the present invention    -   7: CCD or CMOS image sensor    -   8: optical filter    -   9: spectrophotometer    -   10: light    -   11: incident light    -   12: near-infrared cut filter    -   13: transmitted light    -   14: scattered light    -   15: integrating sphere    -   16: sensor    -   17: carbon feather sheet (provided for the purpose of inhibiting        diffused reflection of transmitted light in integrating sphere)

The invention claimed is:
 1. An optical filter comprising: Anear-infrared absorbing dye which comprises a squarylium-based compound(A), and a compound which absorbs fluorescence of the squarylium-basedcompound (A), wherein the absorption maximum of the squarylium-basedcompound (A) is present on the side of shorter wavelength than theabsorption maximum of the compound, wherein the squarylium-basedcompound (A) has the absorption maximum in the wavelength region of notless than 650 nm but less than 740 nm, and the compound has theabsorption maximum in the wavelength region of more than 670 nm but notmore than 760 nm, and the difference in the absorption maximumwavelength between the squarylium-based compound (A) and the compound isfrom 1 to 100 nm, and wherein an average transmittance of the opticalfilter in a wavelength region of from 430 nm to 580 nm is at least 87%,and an average transmittance of the near-infrared cut filter in awavelength region of from 800 nm to 1000 nm is at most 1%.
 2. Theoptical filter according to claim 1, further comprising at least onenear-ultraviolet absorbing agent selected from the group consisting ofan azomethine-based compound, an indole-based compound, abenzotriazole-based compound and a triazine-based compound.
 3. Theoptical filter according to claim 1, which is for a solid-state imagepickup device.
 4. A solid-state image pickup device equipped with theoptical filter according to claim
 1. 5. A camera module equipped withthe optical filter according to claim
 1. 6. The optical filter accordingto claim 1, comprising a resin substrate which comprises a resin, thesquarylium-based compound (A), and the compound.
 7. The optical filteraccording to claim 6, wherein the resin is at least one resin selectedfrom the group consisting of a cyclic polyolefin-based resin, anaromatic polyether-based resin, a polyimide-based resin, a fluorenepolycarbonate-based resin, a fluorene polyester-based resin, apolycarbonate-based resin, a polyamide-based resin, a polyarylate-basedresin, a polysulfone-based resin, a polyether sulfone-based resin, apolyparaphenylene-based resin, a polyamidoimide-based resin, apolyethylene naphthalate-based resin, a fluorinated aromaticpolymer-based resin, a (modified) acrylic resin, an epoxy-based resin,an allyl ester-based curing resin and a silsesquioxane-based ultravioletcuring resin.
 8. The optical filter according to claim 1, wherein theresin substrate is formed on an optical part made of a glass plate,quartz, or transparent plastic.
 9. The optical filter according to claim1, wherein the difference in the absorption maximum wavelength betweenthe squarylium-based compound (A) and the compound which absorbsfluorescence of the squarylium-based compound (A) is from 5 to 80 nm.10. The optical filter according to claim 1, wherein the difference inthe absorption maximum wavelength between the squarylium-based compound(A) and the compound which absorbs fluorescence of the squarylium-basedcompound (A) is from 10 to 60 nm.